Fe-Ti-B esaslı alaşımlarının mekanik alaşımlama yöntemi ile üretimi ve özelliklerinin incelenmesi
Production of Fe-Ti-B based alloys by mechanical alloying method and investigation of their properties
Yazar: ÖZKAN KON
Danışman: PROF. DR. UĞUR ŞEN
Sakarya Uygulamalı Bilimler Üniversitesi / Lisansüstü Eğitim Enstitüsü / Metal Eğitimi Ana Bilim Dalı
Derece: Doktora, 2023
Konu: Metalurji Mühendisliği = Metallurgical Engineering
Dizin: Metal bileşikler = Metal complexes ; Metal eğitimi = Metal education ; Metal tozları = Metal powders

Özet:
Bu çalışmada ferro -Titanyum, ferro -Bor ve saf demir kullanılarak Fe-Ti-B esaslı malzemelerin mekanik alaşımlama yöntemi ile üretilmeleri amaçlanmıştır. İlk olarak kayaç halindeki ferro -Titanyum ve ferro-Bor alaşımları öncelikli olarak nohut tanesi büyüklüğüne gelecek şekilde öğütülmüştür. Ön öğütme işleminin ardından alaşım malzemeleri halkalı değirmende öğütülerek 100 µm elek altı ölçüsüne düşürülmüştür. Deneysel çalışmalarda ASC.100.29 saf demir tozu kullanılmıştır. Deneysel çalışmalarda, kullanılan toz halindeki ferro-titanyum ve ferro-bor tozların öncelikle XRD, SEM, SEM-EDS analiz işlemleri yapılmıştır. Kullanılacak tozlar 130 °C'de 20 saat süreyle etüv fırında kurutularak yoğunluk ölçümleri yapılmıştır. 
Çalışmalarda Fe-Ti-B faz diyagramından yararlanılarak özellikle TiB2 fazının oluştuğu bölgelerden 5 farklı bileşimde hazırlanan tozlar atritör tipi değirmende 350 dev/dk hızda 22 saat süre ile mekanik alaşımlama işlemine tabi tutulmuşlardır. Daha sonra mekanik alaşımlama işlemine tabi tutulmuş kompozit tozların XRD, SEM, SEM-EDS analizleri yapılmış ve BET analizleriyle toz boyut ve yüzey alanları tespit edilmiştir aynı zamandayoğunluk ölçümleride yapılmıştır. Hazırlanan kompozit tozların mekanik alaşımlama işlemleri sonrasında 160MPa basınçla preslenerek, yaklaşık 12 mm çap ve 6 mm yüksekliğe sahip olacak şekilde silindirik olarak üretimleri gerçekleştirilmiştir. Kurutulduktan sonra fırından alınan numunelerin, seramik tüp fırında 6°C/dk ısıtma hızıyla 1400°C sıcaklıkta 60, 180, 300 dakikalık sürelerde basınçsız olarak %99,999 safiyette koruyucu Argon atmosferi altında sinterleme işlemleri gerçekleştirilmiştir. Sinterlenen numunelerin mikroyapı incelemeleri optik mikroskop ve SEM ve EDS analizleri yardımıyla gerçekleştirilmiştir. Ayrıca SEM ile X-ray MAP analiz incelemeleri de yapılmıştır. 
Sinterlenen numuneler, metalografik numune hazırlama işlemlerinin ardından, 10 saniye süre ile 25 gr yük uygulanarak Vickers sertlik ölçümleri gerçekleştirilmiştir. Sertlik değerlerinin tespitinde farklı fazlardan alabilmek için numune üzerindeki renk ton farkından yararlanılmıştır. 
Üretilen kompozit malzemelerin aşınma deneyleri için, ASTM G-99-5 standartlarına uygun ball-on-disk ve pin-on-disk cihazından yararlanılmıştır. Deneyler Ball-on-Disk metodu kullanılarak yapılmıştır. Deneylerde WC- Co bilye kullanılmıştır. Deneylerde numuneler; 0,1 m/s,  0,3 m/s, 0,5m/s hızlarda, 5N, 10N, 15N yük altında 650 metre mesafede gerçekleştirilmiştir. 

Anahtar Kelimeler: Fe2B, FeB, FeTi, Fe2Ti, M/A, TiB2

Abstract:
In this study, it is aimed to produce Fe-Ti-B based materials by Mechanical alloying method by using ferrous titanium, ferrous Boron and pure iron. First, the rocks of ferrous-titanium and ferrous -boron metals were primarily ground to the size of chickpeas. After the pre-grinding process, the alloying materials were ground in a ring mill and ground to 100 µm sieve size. ASC.100.29 pure iron powder was used in experimental studies. In the experimental studies, firstly, XRD, SEM, SEM-EDS characterization techniques on the powders of ferrous -titanium and ferrous-boron were performed. The powders to be used were dried in an oven at 130 °C for 20 hours, and density measurements were realized. Density measurements were done three times and arithmetic averages were taken. As a result of the density measurement, ferrous -titanium was found to be 5.072 gr/cm3, ferrous-boron was 6.011 gr/cm3 and pure iron powder was 7.86 gr/cm3, respectively.
In the studies, powders prepared in 5 different compositions, using the Fe-Ti-B phase diagram, especially from the regions where TiB2 and TiB phases occur, were subjected to mechanical alloying process in an attritor type mill at 350 rpm for 22 hours. Then, XRD, SEM, SEM-EDS characterizations of composite powders prepared in different compositions and subjected to mechanical alloying process were made and BET analyzes were also performed. As a result of BET analysis, 1.1696 m2/gr value was measured for 50Fe-17Ti-33B composite powder. For 50Fe-33Ti-17B composite powder, a width of 0.8131 m2/gr was measured. A value of 0.7053 m2/gr was measured for 50Fe-40Ti-10B composite powder. A value of 0.9807 m2/gr was measured for 50Fe-15Ti-35B composite powder. A value of 0.6607 m2/gr was measured for 50Fe-10Ti-40B composite powder. As a result of XRD analyses, it was observed that, in addition to TiB2 and TiB phases, FeB, Fe2B and FeTi and Fe2Ti phases were formed with the mechanical alloying process. Likewise, the density measurements were made in the composite powders by drying them in an oven oven at 130 °C for 20 hours. Density measurements were made three times and arithmetic averages were taken. As a result of density measurements; For 50Fe-17Ti-33B composite powder, 5.827 gr/cm3 value was measured. The maximum value of 5,635 gr/cm3 was measured for 50Fe-33Ti-17B composite powder. 5,681 gr/cm3 value was measured for 50Fe-40Ti-10B composite powder. For 50Fe-15Ti-35B composite powder, a value of 5.438 gr/cm3 was measured. A value of 5,883 gr/cm3 was measured for 50Fe-10Ti-40B composite powder. In the MA process, the powder/ball ratio was chosen as 1/3 by volume. For the M/A process, 6 mm diameter 52100 steel balls were used.
After the mechanical alloying processes of the prepared composite powders, they were pressed with 160MPa pressure and produced as cylindrical with a diameter of about 12 mm and a height of 6 mm. The samples produced after pressing were dried in an oven at 85°C for 20 hours. After drying, the samples taken from the furnace were sintered in a Protherm brand ceramic tube furnace with a heating rate of 6 °C/min at 1400 °C for 60, 180, and 300 minutes without pressure, under a protective Argon atmosphere of 99.999% purity.
The microstructure examinations of the composites, which were shaped and sintered at 1400 °C and 60, 180, 300 minutes, were carried out with the help of optical microscope and SEM. The produced samples were sanded with 60, 100, 200, 400, 600, 800, 1200 and 2000 grit sandpapers, respectively, for microstructural examination. After sanding, they were polished with 0.3 µm alumina. Afterwards, the samples cleaned with ethyl alcohol were etched with 3% Nital and their microstructures were examined. Along with optical examinations, EDS analyzes of the materials produced by electron microscopy were carried out and their MAPs were taken with SEM. As a result of the analysis, all the desired elements in the produced material were measured. As a result of XRD analysis, it was observed that the ratios of TiB2 and TiB phases increased depending on the time. It was observed that the ratios of some phases decreased depending on the increasing time, and the ratios of TiB2 and TiB phases increased. In the density measurements of the sintered samples, it was observed that the densities increased depending on the increasing sintering time. The lowest 4.8564 gr/cm3 and the highest 4.9756 gr/cm3 values were measured for 50Fe-17Ti-33B composite material. The lowest 5.2701 gr/cm3 and the highest 5.6710 gr/cm3 values were measured for 50Fe-33Ti-17B composite material. The lowest 5.7871 gr/cm3 and the highest 5.8831 gr/cm3 values were measured for 50Fe-40Ti-10B composite material. The lowest 5.8221 gr/cm3 and the highest 6.0928 gr/cm3 values were measured for 50Fe-15Ti-35B composite material. The lowest 5.6986 gr/cm3 and the highest 6.0425 gr/cm3 values were measured for 50Fe-10Ti-40B composite material.
Vickers hardness values of the prepared samples were determined after metallographic processes, which were subjected to sintering under Argon atmosphere at 1400°C for 60, 180, 300 minutes. The load and application time to be used in determining the hardness values were determined after several trials. The hardness of the samples was found by applying 25 gr load for 10 seconds. After the load was applied, the diagonals were determined by using the adjustment buttons of the device and the hardness values were read from the indicator. The hardness values were used from the color tone difference on the sample. The color tone difference showed where the different phases were. At least three measurements were made from each of the regions with color difference and the hardness values were found by taking the arithmetic average of these measurements. The hardness values of the samples increase depending on the sintering time. For the TiB2 phase in 50Fe-17Ti-33B composite material sintered at 1400 °C, the lowest hardnesses of 3580 HV0,025 and the highest 3749 HV0,025 were measured. For TiB2 phase in 50Fe-33Ti-17B composite material, the lowest hardness of 3375 HV0,025 and the highest 3632 HV0,025 were measured. For the TiB2 phase in 50Fe-40Ti-10B composite material, the lowest 3493 HV0,025 hardness, and the highest 3699 HV0,025 hardness were measured. For the TiB2 phase in 50Fe-15Ti-35B composite material, the lowest 3385 HV0,025 and the highest 3793 HV0,025 hardness were measured. For the TiB2 phase in 50Fe-10Ti-40B composite material, the lowest hardness of 3620 HV0,025 and the highest 314 HV0,025 hardness were measured. Among all composite materials, the highest hardness value of Fe2B and FeB phases was measured 1902 HV0,025 and the lowest value was 1568 HV0,025. For the hardness values of FeTi and Fe2Ti phases, the highest value was 890 HV0,025 and the lowest value was 727 HV0,025.
For the wear tests of the produced composite materials, ball-on-disc and pin-on-disk device in accordance with ASTM G-99-5 standards. First, the parts to be abraded were ultrasonically cleaned and dried in an ethyl alcohol bath with a cleaning device for 20 minutes.
Experiments were performed using the Ball-on-Disk method. WC-Co balls were used in the experiments. Samples in experiments; It was carried out at speeds of 0.1 m/s, 0.3 m/s, 0.5 m/s, at a distance of 650 meters under 5N, 10N, 15N loads. The friction coefficients in the wear test were obtained in the computer environment with the load sensors connected to the tribometer device. Microstructure photographs of the wear marks formed as a result of the wear tests were taken. At the same time, the profiles of the wear marks were obtained by measuring them under an optical microscope. Volume losses were calculated by the profiles of the extracted traces. In addition, SEM and elemental analysis of the worn samples were carried out.
For the wear tests, 50Fe-33Ti-17B and 50Fe-10Ti-40B composite materials, which have generally high hardness, were sintered for 5 hours.
The friction coefficient values of 50Fe-33Ti-17B composite sintered at 1400 °C for 5 hours generally increased in direct proportion to the increasing load and speed.
The friction coefficient values of 50Fe-10Ti-40B composite sintered at 1400 °C for 5 hours generally decreased inversely with increasing load and speed. This is because the dominant phase is TiB2. In general, the coefficient of friction in materials was found to be between 0.25 and 0.6. 

Keywords: Fe2B, FeB, FeTi, Fe2Ti, M/A, TiB2