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Sensors and Materials, Vol. 36, No. 8 (2024) 3433–3444
MYU Tokyo
S & M 3742

Effect of Microstructure Changes Caused by Cold Rollingon the Exothermic Characteristics of Al/Ni Multilayer Material
Souto Yamashita,1 Hiroya Saegusa,2 Takahiro Namazu,2 and Shugo Miyake3*
1Department of Mechanical Engineering, Kobe City College of Technology,

8-3 Gakuenhigashi-machi, Nishi-ku, Kobe-shi, Hyogo 651-2102, Japan
2Faculty of Engineering, Kyoto University of Advanced Science,
18 Yamanouchi-gotanda-cho, Ukyo-ku, Kyoto 615-8577, Japan
3Department of Mechanical Engineering, Faculty of Science and Engineering, Setsunan University,
17-8 Ikeda-Nakamachi, Neyagawa, Osaka 572-8508, Japan(Received May 31, 2024; accepted June 24, 2024)

Keywords: Al/Ni multilayer material, self-propagating exothermic reaction, isothermal calorimeter,
standard adding method

In this study, the isothermal reaction calorimetry of an Al/Ni multilayer material fabricatedby an accumulative roll bonding method was performed using an isothermal calorimeter. An
additive method was also devised to measure low-reactivity materials. Calorimetry results forseveral different numbers of cold-rolling passes indicated that the average calorific value of thereaction improved with an increase in the number of rolling passes, and the variance decreased.
The calorific value of the deposited multilayer film, which had a uniform microstructure, wasalso measured. A comparison of the calorific values of the reaction between the powder andfilms showed that, although the films had a uniform structure, the average and variance weresimilar. These results experimentally confirmed that, although the multilayer film is extremely
reactive at Al:Ni = 1:1 atomic composition ratio, the powder and film materials are equivalent
with respect to the total heat generation of the high rolling pass condition.

1.

Introduction

With the widespread use of various electronic devices in our daily lives, electronic control
technology has developed rapidly to address environmental issues and enhance user safety.
Because electronic control devices are installed to improve product safety and convenience,
packaging technology requires high reliability. However, the reflow process, which is mainly
used in the current packaging technology, involves long-term heating using an electronic furnace
or infrared rays. Prolonged heating during the reflow process causes the thermal fatigue of themetal components and warping of the substrate, which may result in joint failure. Furthermore,
the reflow process has an environmental impact because it consumes a significant amount ofelectricity. Therefore, developing a new joining technology that uses a local heating source withlow environmental impact is crucial. In such situations, the self-propagating exothermic reaction*Corresponding author: e-mail: shugo.myake@setsunan.ac.jp

https://doi.org/10.18494/SAM5163

ISSN 0914-4935 © MYU K.K.
https://myukk.org/

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between Al and Ni has attracted attention. Such a reaction is induced by a spark, producing alarge amount of heat with only a small amount of material. Research has been conducted toapply Al/Ni self-propagating exothermic reactions with these characteristics to develop a new
local heating technology.(1–16)
To realize a continuous and uniform self-propagating exothermic reaction of Al/Ni,
fabricating a multilayer Al/Ni structure is necessary. Materials used for self-propagating
exothermic reactions with an Al/Ni multilayer structure are called Al/Ni multilayer materials.
Al/Ni multilayer materials have been proposed in various forms, from powders fabricated bycold rolling and pulverizing methods(5–8) to films deposited by DC magnetron sputtering.(9–16)
In this self-propagating exothermic reaction, when an Al-Ni intermetallic compound isformed, the enthalpies of formation are released as reaction heat. Differential scanningcalorimetry, which uses a heater, is typically used for calorimetric measurements involving
phase changes, such as the Al-Ni self-propagating exothermic reaction.(17–20) However, as
previously mentioned, a key characteristic of self-propagating exothermic reactions is that they
can be induced only by microsparks, having a smaller environmental impact than heater heating.
Therefore, when these materials are applied to joining technology, induction by sparking isassumed instead of using a heater. Therefore, directly measuring the calorific value ofmultilayered materials induced by sparking is considered necessary. This approach allows forthe accurate measurement of both the instantaneous phase change during the reaction and thecalorific value of the reaction associated with compound formation. Therefore, in a previous
study, we developed an isothermal calorimeter capable of directly measuring the calorific valueof multilayer materials induced by sparking.(21) Results from experiments using that calorimeter
showed an increase in calorific value with the number of rolling passes. However, multilayer
powders with low-rolling passes have nonuniform multilayer structures, and some of thepowders used were considered not to react uniformly. Therefore, the calorific value of multilayer
powders with low-rolling passes may have been estimated to be lower than if all the powders had
reacted uniformly. Further investigation of the relationship between the calorific value and thenumber of rolling passes requires ensuring that all the samples react uniformly and theircalorific values are accurately measured, even for samples with low-rolling passes and low
reactivity.
In this study, a method was devised in which a low-rolling-pass sample with low reactivity is
assisted by the addition of a high-rolling-pass material with high reactivity, ensuring that all
samples react uniformly and allowing for the accurate measurement of the calorific value. On
the basis of the results, the relationship between the calorific value and the changes in
microstructure with an increasing number of rolling passes is discussed. In addition, the effectof the uniformity of the multilayer structure on the calorific value is examined by comparing theheat of reaction of a film sample with a uniform multilayer structure to that of a powder sample
fabricated by rolling.

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2.

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Isothermal Calorimeter

We used a modified calorimeter based on an isothermal calorimeter developed in a previous
study. This calorimeter features an isothermal layer made of an acrylic container filled withwater, surrounded by an insulation layer made of commercially available thermal insulationmaterial [with thermal conductivity < 0.035 W/(m･K)], as shown in Fig. 1. A vacuum insulation
vessel with a double-layered insulating structure was fixed in the water tank. The calorimeters
were installed in a climate-controlled laboratory, and the entire system was maintained atthermal equilibrium.
The vacuum insulation vessel inside the tank was filled with an inert liquid that wasconstantly stirred using a magnetic stirrer. The sample cell was made by processing a 12-µmthick polyethylene film. During the reaction of Al/Ni multilayer powders, the polyethylene film
was slightly melted by the exothermic reaction heat. Consequently, the reacted powders diffused
into the inert liquid, which absorbed the reaction heat. The heat of melting of the polyethylene
film used was −51.1 J/g. This film melted approximately 0.01 to 0.02 g during the reaction,
converting to approximately 0.5 to 1.0 J of heat. Therefore, the measurement error due to theheat of melting of this film was evaluated to be very small and negligible. To measure thecalorific value of the reaction, a thermistor (Tateyama Kagaku Kogyo, DS-103) was placed in theinert liquid, and the temperature difference was measured. The calorific value of the reaction
was calculated using the temperature difference of the inert liquids.

3.

Calorimetric Accuracy

3.1

Temperature stability of developed isothermal calorimeter

Figure 2 shows the temperature data of the inert liquid measured by the thermistor in thevacuum insulation vessel and the room temperature data measured by a type-K thermocouple

fluid

Fig. 1.

(Color online) Schematic of isothermal calorimeter.

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Fig. 2.

Temperature stability of developed isothermal calorimeter.

placed near the calorimeter. These data were collected in an air-conditioned laboratory from thestart of air conditioning. The air conditioning was set at 294.15 K. The difference between thetemperature of the inert liquid and the room temperature can be attributed to individual
differences in the type K thermocouple. The type K thermocouple has a temperature resolutionof 0.1 K, and the room temperature changed by approximately 1 K in 24 h. In contrast, thethermistor has a temperature resolution of 0.001 K. The temperature of the inert liquid wasmeasured every 10000 s at eight points with a standard deviation of 0.015 K. If we assume that atemperature change of ±0.015 K occurs in 86400 s (24 h), the temperature change per second isestimated to be ±1.7 × 10−7 K/s. In the measurement, it took approximately 1800 s (30 min) to be
in a thermal equilibrium state with completed exothermic reaction. From this supposition, thetemperature changes during measurement were estimated to be ±0.000306 K. Therefore, thesechanges were kept below the output resolution of the thermistor. Therefore, the heat flux between
room temperature and the inert liquid was considered negligible, and this experimental system
was considered to be in thermal equilibrium, well within the observable range.
3.2

Calculation method for calorific value of the reaction

In this experiment, Al/Ni multilayer powder was reacted with an inert liquid. The calorificvalue of the reaction was calculated from the temperature difference obtained before and after
the reaction and the heat capacity of the inert liquid.
The moving average of the slope was calculated every 250 s from the start of themeasurement. The slope represents the rate of temperature change per second. When the slope isless than 0.000015 K/s, which is 1/1000 of the temperature change of an inert liquid over 24 h,
the liquid is considered to be in a state of sufficient thermal equilibrium. Figure 3 shows thetemperature change in the inert liquid during the measurement. There was an instantaneoustemperature increase near point 2, as shown in Fig. 3. This increase occurred owing to theproximity of the thermistor to the reaction sample, which was measured directly before the heatSensors and Materials, Vol. 36, No. 8 (2024)

Fig. 3.

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Calculation of temperature difference obtained before and after reaction.

diffused into the inert liquid. In this measurement, the temperature difference in sufficient
thermal equilibrium was evaluated; therefore, this noise could be ignored. The point at which therate of temperature change exceeded 0.000015 K/s for the first time since the start of themeasurement was defined as point 1 (250 s before the start of the reaction), and a regression line
was plotted using the slope and intercept at that point. The point on this regression line 250 s
after point 1 was then defined as point 2 (the point at which the reaction started). Next, the pointthat could be considered to be in sufficient thermal equilibrium for the first time after thereaction was defined as point 3. Point 4 (the point at which the reaction ended) was defined frompoint 3 as well as point 2. The temperature difference between points 2 and 4 was defined as thetemperature difference ΔT obtained before and after the reaction.

q=

C ∆T
m

(1)

The temperature difference was multiplied by the heat capacity and divided by the mass ofthe sample used in the reaction to evaluate the calorific value of the reaction per gram, q, as
shown in Eq. (1). In Eq. (1), C is the heat capacity of the inert liquid and m is the sample mass. In
this study, C was calculated by multiplying the mass of the inert liquid used in the experiment by
its specific heat.
3.3

Calorimeter measurement accuracy

The output resolution of the thermistor used in this experiment is ±0.001 K. In addition, theheat capacity of the inert liquid used in the experiment is 525 J/K for 500 g. Therefore, the error
in calorimetric measurement due to the output resolution of the thermistor is approximately±0.525 J, which is sufficiently small compared with the later described calorific value of thereaction, in the range of 1000–1600 J.

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As mentioned previously, this modified calorimeter is highly accurate regarding the expectedcalorific value. Therefore, any variance in the calculated calorific values was considered to besolely due to the sample used in this study.

4.

Effectiveness of Standard Addition Methods in Reaction Experiments

In this section, we describe the calorimetric calculation method for low-rolling-pass powders
used in this study. In calorimetric measurements of powder materials using isothermal
calorimetry, a powder with a low number of rolling passes tends to exhibit low reactivity. The
Al/Ni multilayer powders feature a fine multilayer structure formed by the repeated rolling ofalternating Al and Ni foil layers. However, as shown in Fig. 4, the low-rolling-pass powders
exhibit a nonuniform multilayer structure and discontinuity in the Al/Ni reaction interface.
Therefore, the low-rolling-pass powders were generally less reactive, raising uncertainty
regarding the contribution of all the powders used in the reaction.
In this experiment, we assisted the reaction with a low-reactivity powder by adding 40-passrolling powder, which has high reactivity. This attempt was to evaluate the calorific value of the
low-rolling-pass powder by subtracting the calorific value of the 40-pass rolling powder after
calculating the calorific value.
Figure 5 shows the diffraction peaks of the powder before the reaction, where only the Al andNi peaks were observed. Figure 6 shows the diffraction peaks when the powder was completely
reacted.
When the Al/Ni multilayer powder was fully reacted, the Al and Ni peaks disappeared
regardless of the number of rolling passes, and only the peaks of Al and Ni intermetallic
compounds, such as NiAl and Ni2Al3, were observed.
Thus, even low-rolling-pass powders can fully react through repeated sparking. However, in
actual isothermal calorimetry measurements, a single spark melts the sample cell, and thepowder diffuses into the inert liquid. Therefore, producing repeated sparks to fully react with all
amounts of powder is not feasible. Figure 7 shows the diffraction peaks of the powders that(a)Fig. 4.

(b)

Cross section of Al/Ni multilayer powder material before reaction. (a) 20-pass and (b) 40-pass.

Sensors and Materials, Vol. 36, No. 8 (2024)

Fig. 5. Diffraction peaks of Al/ Ni multilayer
powder before reaction.

Fig. 7.

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Fig. 6. Diffraction peaks of Al/ Ni multilayer
powder after reaction.

Diffraction lines of low-rolling-pass powder reacted in a single spark.

reacted with a single spark. As shown in Fig. 7, the low-rolling-pass powders still exhibited
peaks corresponding to Ni and Al, indicating the presence of the remaining unreacted powder.
However, as shown in Fig. 7, in the case of the sample that reacted by adding 40-pass rolling
powder to the low-rolling-pass sample, the peaks of Ni and Al disappeared after the reaction, andonly the peaks of intermetallic compounds such as NiAl were observed. This suggests that inthis experiment, the addition of 40-pass rolling powder to the low-rolling-pass sample made it
possible to react all the low-reactivity powders in a single spark. The overall calorific value ofthe reaction can be considered as the sum of the reaction heat of the low-rolling-pass powder andthat of the 40-pass rolling powder, as shown in Eq. (2).

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q = ∑ qn
= q20 + q40=(2)

C ∆T20 C ∆T40
+
m20
m40

Because the 40-pass rolling powder was highly reactive, its calorific value was measured
independently and set to a known value. Next, the calorific value of the reaction between the
low-rolling-pass powder and the 40-pass rolling powder was measured, and the calorific value ofthe 40-pass rolling powder was subtracted from the result. The resulting value was calculated as
the calorific value of the low-rolling-pass powder.

5.

Measurement of Calorific Value of the Reaction

5.1

Measurement of calorific value of the reaction of multilayer powder materials

The calorimetric measurements of Al/Ni multilayer powder materials using the previously
mentioned method are described below. In the table, Ave. and Var. represent the average andvariance in three measurements, respectively. The variance of this measurement indicates thevariation in calorific value every sample.
As shown in Table 1 and Fig. 8, the average calorific value of the reaction increased with thenumber of rolling passes. Among the Al-Ni intermetallic compounds, NiAl boasts the highest
enthalpy of formation, reportedly in the range of −60–70 J/mol.(22–26) Therefore, the calorificvalue per gram was estimated at 1634 J/g based on this enthalpy of formation. For the 40-passrolling powder, the average calorific value of the reaction was found to be 1601 J/g, a value inclose alignment with the estimation derived from the enthalpies of formation. Furthermore, thevariance in the calorific value, calculated from repeated measurements, increased as the numberof rolling passes decreased. As shown in Fig. 4, the Al/Ni reaction interface appeared
discontinuous, with the layer thickness showing less uniformity in the 20-pass rolling powder
than in the 40-pass rolling powder. Therefore, it is considered that the nonuniform reaction inwhich Al:Ni is not 1:1 occurs in the 20-pass rolling powder. As a result, it was presumed thatintermetallic compounds with enthalpies of formation lower than that of NiAl, such as Ni2Al3

Table 1
Calorific value of the reaction for each rolling pass of multilayer powder material.
Powder (20-pass)Powder (30-pass)m30 (g) m40 (g) ΔT30 (K) q30 (J/g)
m20 (g) m40 (g) ΔT20 (K) q20 (J/g)
0.026
0.013
0.043
910.3
0.022
0.009
0.055
1316.4
0.022
0.011
0.054
1334.1
0.021
0.012
0.064
1633.8
0.028
0.006
0.079
1537.8
0.031
0.010
0.095
1594.7
Ave.
1260.7
Ave.
1515.0
Var.
320.1
Var.
173.0

Powder (40-pass)m (g)ΔT (K)
q (J/g)0.033
0.094
1656.70.033
0.094
1622.80.026
0.067
1523.4
Ave.
1601.0Var.
69.3

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Fig. 8.

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Calorific value of the reaction for each rolling pass of multilayer powder material.

and Al3Ni, were formed, reducing the overall calorific value of the reaction. However, there were
instances where values close to 1600 J/g were measured for the 20- and 30-pass rolling powders.
This indicates that, in some cases, the reaction is maximized in sample sets containing a highpercentage of powders with atomic composition ratios close to 1:1.
5.2

Calorimetry of multilayer film materials

Next, we describe the measurement results of the Al/Ni multilayer thin films deposited via
sputtering. In this experiment, the Al/Ni multilayer film had an overall thickness of 30 μm and abilayer thickness of 100 nm.
As shown in Table 2 and Fig. 9, the average calorific value of the Al/Ni multilayer reaction is1617 J/g, which is close to the calorific value of the 40-pass rolling powder. This value aligns
closely with the calorific value calculated from the enthalpies of formation. In addition, thevariances of repeated measurements for both the multilayer film and the 40-pass rolling powder
were similar. This indicates that the multilayer powder and multilayer film were comparably
uniform in terms of variations in calorific value. As mentioned previously, the variance incalorific value decreased as the uniformity of the Al/Ni multilayer structure improved with anincreasing number of rolling passes. Here, we compare the cross sections of the multilayer film
and multilayer powder.
Figure 10 shows the SEM cross sections of the multilayer thin film and multilayer powder. As
shown in Fig. 10, the powder shows a multilayer structure with Al and Ni layers spaced 0.5 to 1
Table 2
Calorific values of the reaction of multilayer film and powder (40-pass rolled).
Film
Powder (40-pass)m (g)ΔT (K)
q (J/g)m (g)ΔT (K)
0.029
0.089
1616.2
0.033
0.094
0.035
0.114
1707.6
0.033
0.094
0.034
0.099
1527.2
0.026
0.067
Ave.
1617.0
Ave.
Var.
64.6
Var.

q (J/g)1656.71622.81523.41601.069.3

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Fig. 9.

Calorific values of the reaction of multilayer film and powder (40-pass rolled).

(a)

(b)

Fig. 10. Cross-sectional SEM images of multilayer materials. (a) Film and (b) powder.

µm apart. In contrast, the multilayers in the film are deposited approximately 100 nm apart,which is roughly one-tenth the size of the powder material. Therefore, in terms of microstructure,
multilayer films exhibit greater uniformity than multilayer powders. Furthermore, this highuniformity in the microstructure significantly affects the reaction rate.
Figure 11 shows the results of the exothermal temperature measurements for the powder andfilm materials using a radiation thermometer. The measurement resolution of the radiation
thermometer and data logger is 100 ms. This measurement was started when the exothermic
temperature reached 800 ℃ and was terminated when the temperature fell below 800 ℃. The
maximum temperatures reached by the multilayer powder and multilayer film were comparable,
at approximately 1500 ℃. However, the exothermic response of the multilayer film wascompleted in less than 300 ms, whereas the multilayer powder reached its maximum temperaturein 200 ms but took an additional 1000 ms to complete the reaction. The high reaction rate of themultilayer film is presumably due to its extremely uniform microstructure and continuous
reaction interface. In contrast, powders fabricated by rolling exhibit a nonuniform
microstructure, resulting in a low reaction rate.
However, the previously mentioned calorific value measurement results indicate that the
average and its variance are the same in both the film and the powder. Therefore, in terms ofcalorific value, it is considered that reducing the layer thickness of the powder to 0.5–1 μm

Sensors and Materials, Vol. 36, No. 8 (2024)

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powderFig. 11. Representative temperature curves of multilayer powders and films.

through rolling allows the control of the variance of the calorific value of the reaction to thesame level as that of the multilayer film with a bilayer thickness of 100 nm.

6.

Conclusion

In this study, a modified isothermal calorimeter was developed to measure the calorific valueof the reaction from the self-propagating exothermic reaction of Al/Ni multilayer materials, andboth the multilayer powder and film were measured. Adding 40-pass rolling powder, which has
higher reactivity, to the weakly reactive powder enabled the reaction of all powders with a single
spark. This method enabled us to evaluate the calorific value of the low-rolling-pass powder anddiscuss the relationship between the number of rolling passes and the calorific value.
The measurements of the powder material showed that the maximum value at each rolling
pass closely matched the calorific value estimated from the formation enthalpies in which the
Al:Ni ratio was 1:1. However, for the low-rolling-pass samples, a large variance in the calorificvalue was observed for every sample, which decreased as the number of rolling passes increased.
This variance reduction can be attributed to the increased uniformity of the layer thickness inthe multilayer material with more rolling passes, leading to the improved continuity of thereaction interface. Consequently, this enhancement increased the NiAl ratio in the intermetallic
compound formed by the reaction, thus maximizing the calorific value of the reaction.
We then measured the calorific values of a multilayer film material with a very uniform
multilayer structure fabricated using sputter deposition and 40-pass rolling powder. We foundthat the average calorific values and their variances were comparable. A comparison of the SEM
images of the multilayer powder and film revealed that the multilayer powder was approximately
10 times thicker than the film. From these results, it is considered that reducing the layer
thickness of the powder to 0.5–1 μm through rolling allows the control of the variance of thecalorific value of the reaction to the same level as that of the multilayer film with a bilayer
thickness of 100 nm.

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Acknowledgments
We thank T. Ute and H. Ikushima (Kobe City College of Technology) for their helpful
discussions and sample preparation. We also received generous support from Professor M.
Takashiri (Tokai University) for the measurement of the heat of melting of the polyethylene film.

References
1 J. Wang, E. Besnoin, O. M. Knio, and T. P. Weihs: J. Appl. Phys. 95 (2004) 248. https://doi.org/10.1063/1.1629390
2 J. Wang, E. Besnoin, O. M. Knio, and T. P. Weihs: Acta Mater. 52 (2004) 5265. https://doi.org/10.1016/j.
actamat.2004.07.012
3 R. Knepper, M. R. Snyder, G. Fritz, K. Fisher, O. M. Knio, and T. P. Weihs: J. Appl. Phys. 105 (2009) 083504.
https://doi.org/10.1063/1.3087490
4 B. Boettge, J. Braeuer, M. Wiemer, M. Petzold, J. Bagdahn, and T. Gessner: J. Micromech. Microeng. 20 (2010)
064018. https://doi.org/10.1088/0960-1317/20/6/064018
5 S. Yamashita, R. Yamamoto, and S. Miyake: Jpn. J. Appl. Phys. 60 (2021) SCCL07. https://doi.
org/10.35848/1347-4065/abe996
6 S. Miyake, T. Izumi, and R. Yamamoto: Materials 13 (2020) 4394. https://doi.org/10.3390/ma13194394
7 T. Izumi, N. Kametani, S. Miyake, S. Kanetsuki, and T. Namazu: Jpn. J. Appl. Phys. 57 (2018) 06HJ10. https://doi.org/10.7567/JJAP.57.06HJ10
8 R. Yamamoto, S. Miyake, S. Kanetsuki, T. Namazu, D. Goto, Y. Kuntani, and T. Koganezawa: J. JSEM 19(2019) 30. https://doi.org/10.11395/jjsem.19.30
9 T. Namazu, H. Takemoto, H. Fujita, Y. Nagai and S. Inoue: Proc. 2006 IEEE 19th Micro Electromechanical
Systems Conf. (IEEE, 2006) 286. https://doi.org/10.1109/MEMSYS.2006.1627792
10 T. Namazu, K. Ohtani, K. Yoshiki, and S. Inoue: Proc. 2011 16th Int. Solid-State Sensors, Actuators andMicrosystems Conf. (2011) 1368. https://doi.org/10.4028/www.scientific.net/MSF.706-709.1979
11 K. Ohtani, Y. Yamano, T. Namazu, and S. Inoue: Proc. Transducers (2009) 172.
12 T. Namazu, and S. Inoue: Mater. Sci. Forum 638–642 (2010) 2142. https://doi.org/10.4028/www.scientific.net/
MSF.638-642.2142
13 T. Namazu, K. Ohtani, S. Inoue, and S. Miyake: J. Eng. Mater. Technol. 137 (2015) 031011. https://doi.
org/10.1115/1.4030413
14 K. Maekawa, S. Ito, and T. Namazu: Jpn. J Appl. Phys. 59 (2020) SIIL01. https://doi.org/10.35848/1347-4065/
ab769b
15 S. Miyake, S. Kanetsuki, K. Morino, J. Kuroishi, and T. Namazu: Jpn. J Appl. Phys. 54 (2015) 06FP15. https://doi.org/10.7567/JJAP.54.06FP15
16 K. Maekawa, K. Kodama, S. Miyake, and T. Namazu: Jpn. J Appl. Phys. 60 (2021) SCCL15. https://doi.
org/10.35848/1347-4065/abf39c
17 A. J. Gavens, D. Van Heerden, A. B. Mann, M. E. Reiss, and T. P. Weihs: J. Appl. Phys. 87 (2000) 1255. https://doi.org/10.1063/1.372005
18 H. Sina, K. B. Surredi, and S. Iyengar: J. Alloys Compd. 661 (2009) 294. https://doi.org/10.1016/j.
jallcom.2015.11.105
19 A. Abraham, H. Nie, M. Schoenitz, A. B. Vorozhtsov, M. Lerner, A. Pervikov, N. Podkevich, and E. L. Dreizin:
Combust. Flame 173 (2016) 179. https://doi.org/10.1016/j.combustflame.2016.08.015
20 Z. Ding, Q. Hu, W. Lu, S. Sun, M. Xia, and J. Li: Scripta Mater. 130 (2017) 214. https://doi.org/10.1016/j.
scriptamat.2016.12.010
21 S. Miyake, A. Nagai, and K. Yamada: JSEM 19 (2019) 19. https://doi.org/10.11395/jjsem.19.19
22 A. S. Ramos, M. T. Vieira, J. Morgiel, J. Grzonka, S. Simoes, and M. F. Vieira: J. Alloys Compd. 484 (2009)335. https://doi.org/10.1016/j.jallcom.2009.04.098
23 K. Rzyman, Z. Moser, R. E. Watson, and M. Weinert: J. Phase Equilibria 19 (1998) 106. https://doi.
org/10.1361/105497198770342562
24 K. Rzyman and Z. Moser: Prog. Mater Sci. 49 (2004) 581. https://doi.org/10.1016/j.pmatsci.2003.08.001
25 R. Hu, P. Nash, and Q. Chen: J. Phase Equilibria Diffus. 30 (2009) 559. https://doi.org/10.1007/s11669-0099573-3
26 F. Z. Chrifi-Alaoui, M. Nassik, K. Mahdouk, and J. C. Gachon: J. Alloys Compd. 364 (2004) 121. https://doi.
org/10.1016/S0925-8388(03)00493-6