bluuebunny/crossref_metadata_2025 huggingface dataset:
Fabrication of Ultra-Fine Grained Hot Work Tool Steels by Powder Metallurgy Process through Mechanical Alloying Treatment
Authors: Kataoka Kota , Nakatsu Hideshi
Published: January 2010

Hot work tool steels generally consist of the tempered martensitic structure and they are high strength materials using all strengthening mechanisms, such as strain strengthening, grain refinement strengthening, solid solution strengthening and precipitation strengthening. It is necessary to use the grain refinement strengthening that can bring both higher strength at high temperature and toughness than those of conventional steels. In this study, hot work tool steels with ultra-fine grained structure were fabricated by the mechanical alloying treatment. The powder mixture of atomized AISI H13 steel powders and Y2O3 powders was mechanically alloyed by a planetary ball mill for 360ks. The mechanically alloyed powders were packed in a stainless steel tube in a vacuum and then consolidated by hot rolling for full densification. The consolidated material was austenitized at 1293K, which was general austenitizing temperature of H13 steel, and then oil-quenched. Through this process, an ultra-fine grained H13 steel with equiaxed grains of about 0.3 microns in diameter could be obtained. A quenched hardness of the developed steel was comparable to that of an AISI M2 high speed steel produced by melting and hot-working process. Furthermore, although tempered hardness of the M2 steel decreases with increasing tempering temperature of 848K or higher, that of the developed steel does not decrease so much. Therefore the hardness of the developed steel exceeds that of the M2 steel at tempering temperatures over 923K.
Crystallographic Features of Ferroelectric States around the Tetragonal /Rhombohedral Phase Boundary in Pb1-xLax(Zr1-yTiy)O3
Authors: Arao Masazumi , Inoue Yasuhide , Ando Ryoutarou , Koyama Yasumasa
Published: January 2010

To understand dielectric properties around the ferroelectric tetragonal (FT)/rhombohedral (FR) phase boundary in Pb1-xLax(Zr1-yTiy)O3, the crystallographic features of ferroelectric states around the boundary have been investigated by transmission electron microscopy. It was found that, when the Ti content approached to the phase boundary in the FT-phase area, a dielectric property became the relaxor behavior. The corresponding change in the crystallographic features is that the usual FT state is converted into the nanometer-sized coexisting state of the ferroelectric monoclinic (FM) and FR phases. Because the crystal structure of FR-phase regions in the coexisting state involves the R25-type rotational displacement of oxygen octahedra, the FR phase can be identified as the low-temperature ferroelectric rhombohedral phase that is present in Pb(Zr1-yTiy)O3. It is thus understood that the relaxor behavior found in Pb1-xLax(Zr1-yTiy)O3 should be associated with the presence of the nanometer-sized coexisting state that consists of two ferroelectric phases.
Lasers and Thermal Spray
Authors: Jeandin Michel , Christoulis Dimitris , Borit Francois , Berger Marie Helene , Guetta S. , Rolland G. , Guipont Vincent , Irissou Eric , Legoux Jean Gabriel , Moreau Christian , Nivard M. , Berthe L. , Boustie M. , Ludwig W. , Sakaguchi K. , Ichikawa Y. , Ogawa Kazuhiro , Costil S.
Published: January 2010

Basically, thermal spray and laser processing can be considered as half brothers since they show many common features due to the use of a (more or less) high-energy source for both. Their combination can therefore be very fruitful and prominent to achieve coatings, which results in their most recent and advanced applications. In the materials processing development story, the laser will thus have moved from cutting to coating. This keynote presentation focuses on the recently-developed coupling of laser processing to cold spray). In this dual process, a cold spray gun is combined to a laser head in a single device, e.g. on a robot. Series of coating experiments using various laser irradiation conditions, primarily pulse frequency, were carried out for Al-based and Ni-based alloys. Laser pre-treatment of the substrate just prior to cold spray, was shown to be beneficial for adhesion of cold-sprayed coatings. Adhesion improvement was exhibited and studied from LASATesting (LASAT for “LAser Shock Adhesion Test”). Incidentally, through LASAT also, the role of lasers in the development of thermally-sprayed coatings can be considered as major. Results are discussed in the light of a TEM (Transmission Electron Microscope) study of the coating-substrate interface with and without laser pre-treatment.
Stability of the Orbital-Modulated State in the Layered Perovskite Manganite Sr2-xRxMnO4 (R = Pr, Nd)
Authors: Inoue Yasuhide , Arao Masazumi , Shindo Go , Koyama Yasumasa
Published: January 2010

To understand a stability of the orbital-modulated (OM) state in Sr2-xRxMnO4 (R = Pr, Nd), the crystallographic features of oxide samples with 0.20 < x ≤ 0.50, prepared by the coprecipitation technique, have been investigated by transmission electron microscopy. When the Pr content x corresponding to the eg-electron concentration increased from x = 0, the OM state appeared in 0.20 < x ≤ 0.40 as a neighboring state of an orbital ordered (OO) state around x = 0.20. The interesting features are that around x =　0.44 there is a nanometer-sized coexisting state consisting of the OM and disordered tetragonal (DT) states, and that an average size of OM-state regions in the coexisting state decreases with increasing the eg-electron concentration. In addition, the so-called CE-type antiferromagnetic state found in Sr1.5La0.5MnO4 is absent in the Nd and Pr cases. This suggests that the stability of the OM state is not directly associated with charge ordering of eg electrons, but basically due to only their orbital ordering.
Carbon Nanostructures Produced by an AC Arc Discharge
Authors: Vittori Antisari Marco , Mirabile Gattia Daniele , Brandão L. , Marazzi Renzo , Montone Amelia
Published: January 2010

Carbon nanostructures are under deep investigation due their peculiar properties and possible applications. In particular, development of new methods for the synthesis of these materials and their mechanism of formation represent interesting research fields.
Arc discharge allows to produce different forms of carbon nanostructures. The parameters involved in the process, voltage, current density, type and pressure of the surrounding gas can be controlled especially for achieving high quantity of material with enhanced characteristics in terms of purity while the use of transition metal-graphite mixtures has been used to produce single wall structures. Moreover direct current (DC) and alternating current (AC) are suitable for producing carbon nano-materials, but different results can be obtained. In this work the effect of the power frequency in an AC arc discharge technique on the synthesis of carbon nanostructures is reported. Pure graphite electrodes have been arched in air in an homemade apparatus where the material can be collected directly on a cylindrical collector fixed near the arc. In order to avoid the formation of deposits under the arc a symmetrical configuration of the electrodes has been set. The production of carbon soot containing Single Wall Nanohorns (SWNH) and highly convoluted graphene sheets is optimized. The range of power frequencies 32-1000Hz has been investigated and the arcs have been ignited fixing the voltage at 28 V. The materials has been analyzed by field emission scanning electron microscope and high resolution transmission electron microscope. The microstructure of the material synthesized by this apparatus is affected by the power frequency, as the experimental results demonstrate. The samples produced at low frequency presented high amounts of single wall structures, SWNH-type. More compact structures, similar to large onion-like structures, have been found in samples synthesized at high frequency values.
Measurement of Elastic Constants on Nanostructured Iron and Copper
Authors: Roca Antoni , Lluma Jordi , Jorba Jordi , Llorca-Isern Nuria
Published: January 2010

Measurements of the elasticity modulus and Poisson’s ratio on nanostructured iron obtained by mechanical milling and on nanostructured copper obtained by severe plastic deformation (ECAP) have been carried out. Iron powder was severely deformed in a planetary ball milling. Powder compaction was done in a testing machine, obtaining cylinders that were compacted at temperatures between 425°C and 500°C. Commercial Cu of 99.98 wt % purity was processed at room temperature by Equal-Channel Angular Pressing (ECAP) following the route Bc. Heavy deformation was introduced in the samples after a considerable number of ECAP passes, from 1 to 16. A significant grain refinement was observed after processing the samples. The most important microstructural and mechanical changes were introduced in the first ECAP pass. Elasticity modulus and Poisson’s ratio were determined in iron and copper samples by ultrasonic measurement using an ultrasonic pulser-receiver and two transducers appropriate to the tested materials for pulse-echo sound velocity measurement in longitudinal and shear modes.
Preferred Orientation of Cu2O Nano-/Micro-Protrusions Grown by Ar Ion Irradiation
Authors: Oda Shogo , Tanaka Hiroyuki , Tanaka Shunichiro
Published: January 2010

We have developed a bottom-up growth technology for nanostructures from a Cu surface by Ar ion irradiation. Cu2O conical nano-/micro-protrusions have been nucleated and grown from the surface of a preoxidized Cu plate by Ar ion irradiation in low vacuum. In this study, the growth direction or preferred orientation of the protrusions was analysed using glancing angle X-ray diffraction (GAXRD) analysis and an X-ray diffraction pole figure (XRD-PF) measurement. The GAXRD patterns showed that the main phase of the product obtained by Ar irradiation was Cu2O, shown as the highest peak of Cu2O (111), and CuO was additionally formed. The intensity ratio of Cu2O (110) to Cu2O (111) increased as the X-ray incident angle decreased from 10.0 to 0.5 deg, which indicated that the basal plane of the protrusions including the substrate was (110). Additionally, the XRD-PF {011}<001> 3-D plots showed the <110> preferred orientation of the product. These results explain that the growth direction or preferred orientation of the Cu2O protrusions is mainly <110>. The growth direction of the protrusions was separated and confirmed as <110> by checking the electron backscatter diffraction pattern (EBSP) of each protrusion.
Development of Powder Metallurgy High Nitrogen Stainless Steel
Authors: Kuang Chun Jiang , Zhong H. , Chen D. , Kuang X. , Li Q. , Hao Q.
Published: January 2010

Nitrogen alloying in steel may greatly increase the strength and corrosion resistance of the material. This paper introduced some research results of high nitrogen stainless steel (HNS) investigation via PM process. Nickel free high nitrogen stainless steels (17Cr12Mn2MoN) and superaustenitic high nitrogen stainless steels (28Cr6Mn2/6Mo10/20NiN) were investigated via gas atomization and HIP processes. Nitrogen alloying behavior during atomization and consolidation processes was investigated. Powders with nitrogen content up to 1% were manufactured by gas atomization process. Nickel free high nitrogen stainless steels with nitrogen up to 0.6% exhibits high strength and ductility at as-HIPed and solution annealed state, and superaustenitic HNS with nitrogen content up to 1% showed very high strength and good ductility at solution annealed state, with b at 1100 MPa, s at 810 MPa and elongation of 43%. PM HNS exhibited excellent corrosion resistance.
Comparison of Structure and Properties of Hard Coatings on Commercial Tool Materials Manufactured with the Pressureless Forming Method or Laser Treatment
Authors: Matula Grzegorz , Bonek Mirosław , Dobrzański Leszek Adam
Published: January 2010

The goal of the work is fabrication coatings with the pressureless forming method or laser treatment retaining the relatively high ductility of the coated tool's core. The paper presents selection of the binder portion and type, and also of the metallic and carbides powders (WC) being the constituents of the polymer-powder slurry which was applied onto the prepared surfaces of the test pieces from the conventional HS6-5-2 high speed steel. This materials was compared with the same conventional HS6-5-2 high speed steel heat-treatable steel after laser treatment conditions and alloying additions contained in WC. Investigation indicate the influence of the alloying carbides on the structure and properties of the surface layer of investigated steel depending on manufacturing conditions and power implemented laser (HPDL). In the effect of laser alloying with powders of carbides occurs size reduction of microstructure as well as dispersion hardening through fused in but partially dissolved carbides and consolidation through enrichment of surface layer in alloying additions coming from dissolving carbides. The resistivity to thermal fatique of laser remelted steel is higher than steel after heat treatment. It shows the possibility of applying the worked out technology to manufacturing or regeneration of chosen hot working tools.
Cutting Mechanism of Resin Impregnated Sintered Iron
Authors: Okimoto Kunio
Published: January 2010

Impregnating resin into the open pores of a sintered iron compact is well known to improve the machinability of the compact. However, the causes of this phenomenon require further investigation. The purpose of this study is to clarify the main cause of the improvement in machinability on resin impregnation. In this study, sintered iron was machined and the influences of resin impregnation on its thermal properties, coefficient of friction, and flow stress (deformation resistance) were investigated. The results indicate that the great improvement in machinability produced by resin impregnation is mainly due to a reduction in the plastic deformation (fracture strain) for chip generation, lowering the degree of work hardening and consequently reducing the cutting force required.
Development of Powder Metallurgy High Speed Steel
Authors: Zhong Hai Lin , Fang Y. , Kuang C. , Kuang X. , Hao Q. , Li X.
Published: January 2010

High speed steels (HSS) have been widely used worldwide. This paper introduced some research results of high speed steels via Powder Metallurgy process. High speed steels AHPT15 (W12Cr4V5Co5 ) were investigated via gas atomization, hot isostatic pressing, hot working and heat treatment processes. Microstructure of the steels, precipitation of carbides and the influence of nonmetallic inclusions on mechanical properties of the steels were investigated. PM HSS showed fine and uniform microstructure and exhibited excellent toughness and wear resistance, with bend strength up to 3500 MPa and hardness up to 68.0 HRC.
Influence of Annealing on Strength of Ultrafine Grained Low Carbon Steels by ECAP
Authors: Akita T. , Gotoh Masahide , Dobatkin Sergey V. , Kitagawa Kazuo , Hirose Yukio
Published: January 2010

In the present study, ultra fine-grained low carbon steel samples were processed by equal channel angular pressing (ECAP). Mechanical properties of the specimens annealed statically at several temperatures were evaluated by tensile and hardness test. In addition, grain sizes of the specimens were measured by SEM-electron back scattering pattern (SEM-EBSP) and X-ray diffraction analysis. Differential scanning calorimetry (DSC) measurement also evaluated thermal reactions in anneal process of the specimen. As a result, the grain size was changed at the temperature between 550oC and 600oC drastically and the tensile strength also became lower at the same temperature. The relation between yield stress and averaged grain diameter of specimens obeyed the Hall-Petch relation except the normalized specimen. Behavior of grain growth and recovery in structural observation by EBSP corresponded to reaction signal of the DSC curve.
Recrystallization Mechanisms in Severely Deformed Dual-Phase Stainless Steel
Authors: Belyakov Andrey , Kaibyshev Rustam , Kimura Yuuji , Tsuzaki Kaneaki
Published: January 2010

The structural recrystallization mechanisms operating in an Fe – 27%Cr – 9% Ni dual-phase (ferrite-austenite) stainless steel after large strain processing to total strain of 4.4 were investigated in the temperature range of 400-700oC. The severe deformation resulted in the development of an ultrafine grained microstructure consisting of highly elongated grains/subgrains with transverse dimensions of 160 nm and 130 nm in ferrite and austenite, respectively. The annealing mechanism operating in ferrite phase was considered as continuous recrystallization, which involved recovery leading to the development of essentially polygonized microstructure. On the other hand, the mechanism of discontinuous nucleation took place at an early recrystallization stage in austenite phase.
Improvement in Drawability (r Value) of an Aluminum Alloy Subjected to Groove Pressing
Authors: Niranjan Ganesh , Uday Chakkingal
Published: January 2010

There is increasing interest in using Al alloy sheets for auto body applications. However Al alloys exhibit poor drawability as indicated by low values of the normal anisotropy, rm. Techniques for improving the value of rm rely on developing a favourable shear texture in the sheet. In this study, Al alloy AA 6061 sheets of dimensions 225 mm x 200 mm and 1 mm thick were subjected to severe plastic deformation by repeated groove pressing using a set of grooved and flat dies alternatively. The orientation of the grooves with respect to the rolling direction was also varied. Microstructure characterization and mechanical property measurements were carried out. X- ray diffraction scans were carried out to measure the relative intensities of the (111) and (200) peaks. The r values was measured as per ASTM standard E 517 on strip specimens cut at 0°, 45° and 90° to the rolling direction and the normal anisotropy value (rm) and planar anisotropy value (Δr) values were determined. The limiting drawing ratio (LDR) was determined using the Swift cupping test techniques. It was observed that the rm values increased from 0.72 in the as received condition to a maximum of 0.94 and the LDR increased from 1.93 to 2.06 when the groove pressing was carried out with grooves at to 45° the rolling direction. The improvement in rm values can be correlated to the texture developing in the sheet as a result of severe plastic deformation.
Dislocation-Source Hardening in Nanostructured Steel Produced by Severe Plastic Deformation
Authors: Kamikawa Naoya , Huang Xiao Xu , Hansen Niels
Published: January 2010

Annealing-induced hardening and deformation-induced softening behavior has recently been found in nanostructured aluminum (fcc) produced by severe plastic deformation. It has also been demonstrated that annealing led to a decrease in ductility while deformation led to an increase in ductility. These mechanical responses are totally opposite to those in conventional coarse-grained samples. The present study explores the effect of post-process annealing or deformation on mechanical properties of nanostructured interstitial free (IF) steel (bcc). Accumulative roll-bonding was used to produce the nanostructured IF steel. The deformation structure was characterized by a lamellar boundary structure with a mean spacing of about 200 nm, consisting of high-angle boundaries, low-angle dislocation boundaries and dislocations in the volume between the boundaries. When the deformed sample was annealed at 400oC for 0.5 h, the yield stress and ultimate tensile strength increased and the elongation to failure decreased markedly. In contrast, when the annealed treatment was followed by a light rolling deformation of 15 % thickness reduction, the strength decreased and the elongation to failure increased. These results are consistent with those observed in the aluminum samples. Structural observations by transmission electron microscopy indicated that a removal of dislocations between the boundaries leads to a lack of dislocation sources, resulting in a higher stress to activate alternative dislocation sources. It was suggested that deformation rather than annealing could be a new route to improve the ductility of nanostructured metals and that a moderate light deformation gives a good balance of strength and ductility.
Grain Boundary Texture
Authors: Randle Valerie , Jones Richard
Published: January 2010

Recently the distribution of grain boundary planes in metals and other materials has begun to be studied in addition to the misorientation distribution. It has been found that a ‘grain boundary texture’, i.e. a non-random distribution of grain boundary planes, often exists. The present paper will show examples of grain boundary texture taken from austenitic stainless steel and rocksalt. The characteristics of the grain boundary texture will be described in terms of low-index boundary planes and tilt/twist descriptors. Reasons for the formation of the particular grain boundary texture and possibilities for exploitation via grain boundary engineering will be discussed.
Characteristics of High Temperature Creep in Pure Aluminum Processed by Equal-Channel Angular Pressing
Authors: Kawasaki Megumi , Langdon Terence G.
Published: January 2010

High purity aluminum was processed by equal-channel angular pressing (ECAP) to reduce the grain size to ~1.3 m. Tensile specimens were cut from the as-pressed billets and these specimens were tested under conditions of high temperature creep. The results show excellent creep properties with a well-defined region of steady-state flow. The flow behavior is analyzed by comparing the creep data with the predicted behavior for different fundamental creep mechanisms and by plotting a deformation mechanism map to provide a visual representation of the creep properties.
Grain Refinement Efficiency in Equal Channel Angular Extrusion of FCC Metals Inferred from Crystal Plasticity Simulations of Slip Activities
Authors: Li Sai Yi
Published: January 2010

Equal channel angular extrusion (ECAE) is a relatively new technique to produce ultrafine-grained materials by severe plastic deformation. Its efficiency of grain refinement varies with the processing route, i.e. the billet rotation () about its longitudinal axis between successive passes. The influence of processing route can not be fully explained by existing theories that consider only the macroscopic deformation features. In this study, the mesoscopic deformation behavior during multi-pass ECAE of face-centered cubic (FCC) metals was simulated using a visco-plasticity self-consistent (VPSC) polycrystal model and assuming simple shear deformation in each pass. It is shown that the slip activities vary significantly at the transitions between successive passes, depending on the die angle and processing route. The efficiencies of grain refinement in the different cases can be well correlated to the contribution of slip systems newly activated in a subsequent pass. The grain refinement is more efficient when such contributions are higher, such as in route B ( = 90) with a 90 die or route A ( = 0) with a 120 die. These crystal plasticity simulations provide insights into the efficiency of grain refinement during severe plastic deformation with strain path changes.
Thermo-Mechanical Problem of Torque in Beam with Annular Cross-Section
Authors: Stropnik Joze , Kosel Franc
Published: January 2010

The paper deals with the problem of the torque in the cantilever beam with annular cross section in the elasto-plastic domain, considering the material with elastic-linear hardening model. The cantilever beam is subjected to the alternating load of such frequency that the heat is generated in the beam. The quantity of the generated heat depends on the amplitude of the torque, frequency of the load and mechanical properties of the beam material. Equations which relate the value of the torque to the extent of the plastic region of the cross section and the shearing stresses of the beam in the elasto-plastic domain are given. Furthermore, equations for deformation work, transformation work, energy due to residual stresses and energy transformed into heat are presented. The article compares results concerning the temperature change at characteristic points along the beam, obtained via numerical analysis as well as experimentally.
Effect of Preliminary Treatment on Grain Refinement of Medium Carbon Steel Using ECAP at Increased Temperature
Authors: Zrník Jozef , Dobatkin Sergey V. , Fujda Martin , Džugan Jan
Published: January 2010

By application of thermomechanical controlled rolling and accelerated cooling, the carbon steel grain refinement is limited to levels of ~ 5 μm in steels. The strain assisted or strain induced transformation could be considered for the refining process. The present work, likewise, deals with grain refinement of medium carbon steel containing 0.45 wt pct carbon having different initial microstructure modified by either thermal and/or thermomechanical treatment (TM) prior severe plastic deformation. In case of TM treated steel, structure refinement was conducted in two steps. Preliminary structure refinement has been achieved due to multistep open die forging process which provided total strain of 3. Uniform and fine recrystallized ferrite structure with grain size of the order of 2-5 μm and with nest-like pearlite colonies was obtained. The further grain refinement of steel samples having different initial structure was accomplished during warm Equal Channel Angular Pressing (ECAP) at 400°C. The steel samples of different initial structure were then subjected to six ECAP pressing passes through die channel angle of 120°. The microstructure development was analyzed in dependence of effective strain introduced (εef ~ 2.5 - 4). Employment of this processing route resulted in extensive deformation of ferrite grains where mixture of subgrains and ultrafine grain was found regardless the preliminary treatment of steel. As straining increases the dynamic polygonization and recrystallization became active to form mixture of polygonized subgrains and submicrocrystalline grains having high angle boundaries. The straining and moderate ECAP temperature caused the partial cementite lamellae fragmentation and spheroidization as straining increased. The lamellae cementite spheroidization was more extensive in TM treated steel samples. The tensile behavior was characterized by strength increase for both structural steel states; however the work hardening behavior was modified in steel where preliminary TM treatment was introduced to modified coarse ferrite-pearlite structure.
Application of a High Magnetic Field during Thermo-Treatment of Metallic Materials as a Potential Means for Microstructure Modification
Authors: Zhang Yu Dong , Esling Claude , Zhao Xiang , Zuo Liang
Published: January 2010

In this paper, some of our recent results in phase equilibrium, microstructure, texture and precipitation resulting from the application of an external high magnetic field during diffusional phase transformation in both medium carbon and high carbon steels have been summarized Their potential engineering applications are foreseen.
Structure and Phase Stability of NiMnGa Ferromagnetic Shape Memory Alloys by Experimental and Ab Initio Techniques
Authors: Esling Claude , Cong Dao Yong , Bai Jing , Zhang Yu Dong , Raulot Jean Marc , Zhao Xiang , Zuo Liang
Published: January 2010

This paper summarizes some of our recent results on crystal structure, microstructure, orientation relationship between martensitic variants and crystallographic features of martensitic transformation in Ni-Mn-Ga FSMAs. It was shown that Ni53Mn25Ga22 has a tetragonal I4/mmm martensitic structure at room temperature. The neighboring martensitic variants in Ni53Mn25Ga22 have a compound twinning relationship with the twinning elements K1={112}, K2={11-2}, η1=<11-1>, η2=<111>, P={1-10} and s=0.379. The ratio of the relative amounts of twins within the same initial austenite grain is ~1.70. The main orientation relationship between austenite and martensite is Kurdjumov-Sachs (K-S) relationship. Based on the crystallographic phenomenological theory, the calculated habit plane is {0.690 -0.102 0.716}A (5.95° from {101}A), and the magnitude, direction and shear angle of the macroscopic transformation shear are 0.121, <-0.709 0.105 0.698>A (6.04° from <-101>A) and 6.88°, respectively.
Effect of Carbon Addition of Shape Memory Properties of TiNb Alloys
Authors: Hosoda Hideki , Horiuchi Yosuke , Inamura Tomonari , Wakashima Kenji , Kim H.Y. , Miyazaki Shuichi
Published: January 2010

In order to increase critical stress for slip in Ti-Nb base shape memory alloys, strengthening by carbon additions (0.2 and 0.5mass%C) to Ti-27mol%Nb was investigated. It was found that all the alloys were  (bcc) phase at room temperature, and TiC existed in C-added alloys. The grain size was decreased with carbon content due to grain boundary pinning. Texture measurement revealed that strong {112}<110> recrystallization texture was formed in C-free alloy and that weak {001}<110> texture in C-added alloys. Tensile tests revealed that clear superelasticity appeared in C-free alloy but that stress-induced martensitic transformation seems to be suppressed by TiC in C-added alloys. The critical stress for slip was linearly increased by carbon content. Then, carbon addition affects the shape memory properties of TiNb alloys, and is effective to enhance the critical stress for slip.
Design of Joint Properties by Friction Powder Processing
Authors: Inada Koji , Fujii Hidetoshi , Ji Young Su , Morisada Yoshiaki , Nogi Kiyoshi
Published: January 2010

Friction powder processing (FPP) has been developed based on the principle of friction stir welding (FSW) or friction stir processing (FSP). The FPP is a method to design the properties of the processed area by performing FSP after powder with a controlled composition is placed in the gap between two plates. The FPP experiments were performed using a tool with the shoulder diameter of 15mm and the probe diameter of 6mm. The tool traveled at 100mm/min and rotated at 1500rpm. A1050 aluminum was used as the plate. Pure Al powder (89μm average grain diameter) and pure Cu powder (106μm average grain diameter) were used as the additives. When using pure Al powder, the pure Al powder left in the base metal after the first pass is sufficiently stirred by performing the second pass and then a good joint without defects is obtained. However, more than three passes are not effective for improving the strength of the welded area. When using pure Cu powder, nanoscale Al2Cu precipitates are uniformly formed in the stir zone, and accordingly, the hardness is significantly increased.
Heating Behaviors of Powdered Metal Silicon Compact Under Microwave Irradiation
Authors: Kunieda Yoshihiko , Shimofuruya Hiroshi , Tanigawa Tomoyuki , Ito Yasuyuki
Published: January 2010

The use of microwave heating has now been applied to a wide variety of industrial fields. Especially, the use of microwave energy for the firing process of the advanced ceramics has been reportedly found to offer significant advantages compared to the conventional thermal heating. Generally, in the volume production, we use the suscepor, which is the pyrogenetic substance to be heated the specimens externally and to play a very important role in firing ceramics. Recently, we found out that the powdered metal silicon compact is one of the good candidates as susceptor materials. However, its microwave heating mechanism has not been made clear, yet. Then, in this report, we carried out the fundamental studies about the heating behaviors of the powdered metal silicon compact mixed with aluminum oxide powder under the microwave irradiation at a frequency of 2.45GHz in a symmetrical single mode cavity TE01 and the analysis of products after heating by the X-ray diffraction method. From experimental results, it was found out that the attained temperature of the compact specimen under microwave irradiation was higher with increase of voltage along the voltage distribution in the single mode cavity. And it was also found out that the temperature was different with how to set up the compact specimen in the single mode cavity.
Influence of High Melting Glasses on Selected Properties of PtRh-Alloys for Application in Glass Fiber Bushings
Authors: Merker Jürgen , Scheckenbach C. , Fischer Bernd , Lupton David F. , Kravchenko Iryna
Published: January 2010

For the production of endless glass fibres, the use of glass fibre bushings made of PtRh alloys is necessary. The manufacturing process for high melting glass fibres in particular leads to simultaneous chemical attack and mechanical loading at extremely high temperatures.The influence of these complex loadings on the stress-rupture strength and the creep behaviour of various PtRh alloys (conventional and oxide dispersion strengthened alloys) was investigated after contact with various glass melts. The investigations include both long-term tests under service conditions and laboratory corrosion tests. The investigations will be complemented with metallographic and fracture examinations in the SEM and microprobe analysis.Furthermore, the fibre manufacturing process is influenced by the wetting of the bushing material by the glass melt. For this reason the wetting behaviour of the platinum materials in contact with the different glass melts was investigated as a function of the working temperature of the glass fibre bushings. The results of the investigations provide a basis to optimise materials selection for glass fibre bushings.
Influence of Internal Pulsed Current on the Sintering Behavior of Pulsed Current Sintering Process
Authors: Misawa Tatsuya , Shikatani Noburo , Kawakami Yuji , Enjoji Takashi , Ohtsu Yasunori
Published: January 2010

To clarify the influence of internal pulsed current upon the sintering behavior of powder materials during spark plasma sintering processing, simultaneous measurement of internal current using magnetic probe was carried out. Magnetic probe is installed to the side of the sintering ZnO powder material through the carbon graphite sintering die, and detects the magnetic field generated by internal current which flow through the specimen. By magnetic probe measurement, the internal current that flows through the specimen during SPS process was several hundred ampere, and the ratio of the internal current to the total current was found to be dependent on the electrical conductivity, diameter of powder material and the progress of SPS process. The measurement and estimation of an internal pulsed current using a magnetic probe in the specimen is very useful for in situ observation of the sintering behavior during the SPS process.
Al/Ni Self-Propagating Exothermic Film for MEMS Application
Authors: Namazu Takahiro , Inoue Shozo
Published: January 2010

This paper describes evaluation of the strength in Ag-Sn-jointed Si specimens heated by Al/Ni film’s exothermic reaction. The reaction generates heat enough to melt Ag-Sn film for soldering. To measure the strength, four-point micro-bending test technique has been developed. The rectangular-solid Si specimens having a Ag-Sn/AlNi/Ag-Sn section were prepared by dicing the bonded Si-wafer under various pressure loads. A higher pressure yielded a better contact condition between Al/Ni and Ag-Sn so that heat-conduction improved; consequently Ag-Sn was melted sufficiently. Al/Ni reactive film has a potential as a micro-heater in soldering for MEMS.
(Zn,Mn)Te-Based Nanowires for Spintronic Applications: A TEM Study of Structural and Chemical Properties
Authors: Kirmse Holm , Neumann Wolfgang , Kret Slawomir , Janik Elzbieta , Zaleszczyk Wojciech , Karczewski Grzegorz , Wojtowicz Tomasz
Published: January 2010

(Zn,Mn)Te nanowires were grown via vapor-liquid-solid mode as test structures for spintronic applications. The structural and chemical properties of the nanowires were inspected by transmission electron microscopy. The nanowires contain much less stacking faults compared to ZnTe nanowires. This high structural perfection can be attributed to a rough liquid-solid interface as found by high-resolution transmission electron microscopy. The composition of the nanowires and, in particular, the Mn distribution is homogeneous. A ZnO cover layer forms after the growth of the nanowires.
Fabrication of Cu-Based Functionally Graded Materials Dispersing Fine Sic Particles by a Centrifugal Mixed-Powder Method
Authors: Sato Hisashi , Inaguma Yoshifumi , Watanabe Yoshimi
Published: January 2010

Recently, a centrifugal mixed-powder method has been proposed as the processing technique of functionally graded material (FGM) containing fine solid-particles. In this study, Cu-based FGM containing SiC particles was fabricated using this technique. Although the density of SiC is smaller than that of Cu, these SiC particles are successfully distributed on surface of the cylindrical FGM. From this result, it is clear the movement of solid particle in powder mixture during casting is small. Therefore, the gradual distribution of the solid particle can be formed by the control of the volume fraction of solid-particles in powder mixture. Also, it is found that smaller SiC particle can improve the hardness on the surface of the FGMs effectively rather than larger one. In this study, the assignment of the centrifugal mixed-powder method was suggested from the obtained results.
FEM Analysis of Joint Interface Formation in Magnetic Pressure Seam Welding
Authors: Serizawa Hisashi , Shibaharar Isao , Rashed Sherif , Murakawa Hidekazu
Published: January 2010

The magnetic pressure seam welding is one of the candidate methods to join thin sheet smart and multifunctional materials. In this research, to examine the mechanism of magnetic pressure welding from a dynamic viewpoint, numerical simulation of the impact was carried out by using a commercial Euler-Lagrange coupling software MSC.Dytran (MSC.Software) as a first step of the computational studies, where the joint between Fe and Al was employed according to the previous experimental researches. From the serial numerical results, it was found that the increase of temperature at the joint interface was not enough to melt Al or Fe in the range of collision velocity and angle studied in this report. Also, it was revealed that the very large mean stress occurred at the interface which could be considered as the pressure at joint interface and Al moved with high velocity along the interface. Moreover, it was found that there were two patterns of plastic strain distribution near the joint interface depending on the collision velocity and collision angle. Finally, it can be concluded that the plastic strain pattern might be related to the success of magnetic pressure seam welding.
Fabrication and Two-Way Deformation of Shape Memory Composite with SMA and SMP
Authors: Tobushi Hisaaki , Hayashi Shunichi , Sugimoto Y. , Date K.
Published: January 2010

The shape memory composite (SMC) with shape memory alloy (SMA) and shape memory polymer (SMP) was fabricated, and the two-way bending deformation and recovery force were investigated. The results obtained can be summarized as follows. (1) Two kinds of SMA tapes which show the shape memory effect and superelasticity were heat-treated to memorize the round shape, respectively. The shape-memorized round SMA tapes were sandwiched between the SMP sheets, and the SMC belt was fabricated. (2) The two-way bending deformation with an angle of 56 degrees is observed during heating and cooling. (3) If the SMC belt is heated and cooled by keeping the form, recovery force increases during heating and decreases during cooling.
Mechanical Behaviour of Metals under Explosive Loading
Authors: Montanari Roberto , Ucciardello Nadia
Published: January 2010

The paper briefly examines the metallurgical effects of shock waves on different metals. Two points are then specifically addressed. The first one regards how X-ray diffraction (XRD) can be usefully employed to get exhaustive information about the microstructure of a shock loaded metal. The second point concerns the mechanisms of martensitic transformation in alloys such as AISI 304 when submitted to repeated explosive deformations.
Mechanisms of New Grain Formation in a Ni-20%Cr Alloy during Warm to Hot Working
Authors: Dudova Nadezhda , Kaibyshev Rustam , Belyakov Andrey
Published: January 2010

The process of new fine grain formation was studied in compression of a Ni-20%Cr alloy at temperatures ranging from 500°C (0.46Tm) to 950°C (0.73 Tm) at a strain rate of 710-4 s-1. Two types of deformation behaviors with different features of microstructure evolution were observed, depending on processing conditions. The deformation behavior under flow stresses below about 500 MPa (relatively high temperatures) was typical for hot working associated with discontinuous dynamic recrystallization (DRX). The extensive local migration (bulging) of both initial and deformation induced high angle boundaries (HAGBs) resulted in the development of nuclei, which grew out leading to the formation of recrystallized structure with grain size of D > 1 m. Numerous annealing twins were observed within these DRX grains. On the other hand, continuous DRX gave a major contribution to the formation of new grains at applied stresses above 500 MPa (relatively low temperatures). This fact was attributed to a low mobility of grain boundaries. The new grains with size of D < 1 m were evolved due to gradual transformation of deformation induced low angle boundaries (LAGBs) into HAGBs.
Simulation of the Solidification Parameters of Single Crystal Casting
Authors: Jin H.P. , Li Jia Rong , Liu Shi Zhong
Published: January 2010

The effects of thermal physical parameters and boundary conditions on investment solidification parameters were obtained using a computer simulation system. Directional solidification parameters of single crystal superalloy include the temperature distribution, the position and the shape of the solid/liquid interface in the mushy zone of the solidifying blade casting. Commercial finite-element analysis software, ProCAST, was used to simulate the solidification processes of the castings of single crystal DD6. The simulation results indicate that the predictions of the temperature show little sensitivity to the thermal physical parameters and boundary conditions. Further, it has also been shown that the location and the shape of solid/liquid interface is related to the boundary conditions of simulation. Increasing the value of interface heat transfer coefficient decreases the width of mushy zone.
Role of Rhenium in Single Crystal Ni-Based Superalloys
Authors: Jin Tao , Wang Wen Zhen , Sun Xiao Feng , Hu Zhuang Qi
Published: January 2010

The effect of rhenium on the microstructure and mechanical properties of single crystal superalloys with a nominal composition of Ni-3Cr-12Co-1Mo-6W-6Al-8Ta-0.1Hf-(0, 2, 4) Re has been studied. With the rise of rhenium content, the size of as-cast  particles becomes smaller. Rhenium addition elevates the incipient melting temperature and slows down the solid solution process. Even after 2000h prolonged aging both at 950°C and 1050°C, no topologically close-packed phase precipitation is found in the three alloys with Re content up to 4%. Re retards the  coarsening and is beneficial to improving the stress rupture life. The deformation mechanisms together with the dislocation configuration have been studied and discussed.
Fabrication Process for a High Strength 9Cr-2W Steel Sheet
Authors: Kim Tae Kyu , Han Chang Hee , Kim Sung Ho , Lee Chan Bock
Published: January 2010

This study deals with the fabrication of high strength ferritic/martensitic steels by a control of both the carbon concentration and the fabrication process parameters. The 9Cr-2W steels containing a carbon concentration of 0.05, 0.07 and 0.11 wt% were normalized at 1050oC for 1 h, followed by a tempering at 550 and 750oC for 2 h, respectively. The results of the tensile tests at room temperature indicated that the tensile strengths were increased with an increase of the carbon concentration from 0.05 wt% to 0.07 wt%, but no more increase was observed when the carbon concentration was increased further up to 0.11%. After a cold rolling from a 4 mm to a 1 mm thickness without/with an intermediate heat treatment and a final heat treatment, the results of the tensile tests exhibited that superior tensile properties were obtained when the fabrication processes were composed of a tempering at 550oC, and a cold rolling with several intermediate heat treatments. These results could be attributed to the finely distributed precipitates in the partially recrystallized matrix. The optimized carbon concentration and the controlled fabrication process parameters are thus suggested to fabricate a high strength 9Cr-2W steel sheet.
Dislocation Substructure of Single Crystal Ni-Based Superalloy, CMSX-4, Crept at 1073-1273K and 250-600MPa
Authors: Kondo Y. , Miura N.
Published: January 2010

The rate controlling mechanism for creep deformation of the single crystal Ni-based superalloy, CMSX-4, at 1073-1273K and 250-700MPa was investigated. Constant load tensile creep tests and creep interrupted tests up to the minimum creep stage, were conducted in air. And TEM observations carried out on creep interrupted specimens. Stacking faults in the ’ were observed on creep interrupted specimens at the temperature lower than 1223K and the stress higher than 500MPa. The number of stacking faults increases monotonously with a decrease in temperature, and remarkably with an increase in stress. The stacking fault formation depends on creep temperature and stress conditions. The stress exponent of minimum creep rate, n value, and the activation energy for creep, Qc, were constant for all creep test condition range. From these results, the stacking fault formation has no influence on creep resistance and the rate controlling mechanism for creep deformation at the low temperature and high stress condition was not thought to be shearing the ’, but movement of the mobile dislocations in the  channel as well as at the high temperature and low stress condition.
Phase-Separation of B2 Precipitates in an Fe-Ni-Al Alloy
Authors: Kuno Yasuhiro , Nakane Yasuo , Kozakai Takao , Doi Minoru , Yamanaka Junji , Yamamoto Chiaya , Naito Shizuo
Published: January 2010

When Fe-10.3mol%Ni-14.3mol%Al alloy is heated at 1173 K for 8.64104 s, a number of B2 precipitates are dispersed in the A2 matrix. When the two-phase microstructure of A2+B2 is aged at 973 K, the phase-separation of B2 precipitate particles takes place to form a new A2 phase in each B2 particle. In the course of further ageing at 973 K, the new A2 phase grows but decreases in number, and finally only one A2 particle is left in the individual B2 particles. The appearance of new A2 phase in each B2 precipitate is due to the difference in the volume fraction of A2 phase that should exist in A2+B2 two-phase system depending on the heating temperature: i.e., the phase-separation of B2 precipitates starts with the aid of chemical free energy.
Analysis of Creep Curves of Haynes 230 Superalloy
Authors: Maldini Maurizio , Angella Giuliano , Lupinc Valentino
Published: January 2010

The creep behaviour of the solid solution strengthened nickel-based superalloy Haynes 230 has been investigated under constant load and temperature conditions on as received, after conventional solution treatment, and on overaged conditions. The experimental results have shown a very strong dependence of the creep curve shape with the applied stress/temperature: in the tests performed at high stresses/low temperatures, the primary/decelerating stage takes an important portion of the creep curve. At these test conditions, the accelerating creep is mainly caused by the increase of the applied stress with the strain as it happens in constant load creep tests. In the tests performed at low stresses/high temperatures, the primary stage is very small and the following accelerating creep is characterized by different accelerating creep stages. The analysis of the creep curves on the as received and overaged alloys, has shown that a large portion of the accelerating creep at low stresses/high temperatures is caused by microstructural instability.