Characteristics and applications of Fe-Mn-Si-based shape memory alloys
AWAJI MATERIA CO., LTD.
(1) Introduction
Fe-Mn-Si based shape memory alloy (Fe-Mn-Si

Table 1. Main compositions of
Fe-Mn-Si SMAs (mass%)

SMA) is known as the only material in practicaluse among iron-based shape memory alloys. The

Fe-32Mn-6Si

basic components are Fe, 32% Mn, and 6% Si,

Fe-28Mn-6Si-5Cr*

which are the base components, but alloys with

Fe-20Mn-5Si-8Cr-5Ni

added Cr and Ni have also been developed in

Fe-16Mn-5Si-12Cr-5Ni

terms of corrosion resistance (Table1). Most of*Currently only Fe-28Mn-6Si-5Cr is
manufactured

the studies on practical application are being

carried out using Fe-28Mn-6Si-5Cr alloy(mass%) and only this alloy is currently
manufactured.
It is noteworthy that this alloy has been mainly carried out in Japan from the discovery1)
and development of materials to its application. Since it does not contain elements that are
expensive in composition and can be produced using mass production equipment for steel andstainless steel, it can be said that it is an inexpensive material for mass production as an SMA.
However, it does not mean that the limited usage and material costs in the early stages ofsmall-scale production are comparable to ordinary steel and stainless steel. This is because
these mass production facilities cannot be used unless the production scale commensuratewith them is secured.
Although the shape recovery strain of the Fe-Mn-Si SMA is not as high as that of the Ti-Ni
alloy, a maximum of about 4% can be obtained (when the training treatment described later isapplied). Moreover, since there is little difference in the strength of the material before andafter phase transformation, bidirectional operation using the bias spring cannot be expected.
Furthermore, the temperature for shape recovery requires a higher temperature than the
Ti-Ni alloy, and the shape recovery gradually progresses over a wide temperature range fromabout 90 ° C to 350 ° C. As a field in which the above characteristics of Fe-Mn-Si SMA can beutilized, application to relatively large
Applications,

therefore,aremainlyconsidered as relatively-large components
to take advantage of such characteristics.
(2) Mechanisms of shape memory
The temperature dependence of 0.2%

Yield stress, /MPaconnecting members is being focused on.
as solution treatedfour-times-training treated

Yield stress of parent phase

Critical stress formartensitic transformation

proof stress of the Fe-Mn-Si SMA shows acharacteristic shape as shown in Fig.12)
Looking from room temperature to higher
temperature, there is a region where the
0.2%

proof

stressincreasesastheTemperature (K)Fig. 1The dependence of yield stress on
temperature2）

temperature rises in the range up to a certain temperature, and beyond that, 0.2% proof
stress will be reduced as ordinary steels. Two different slopes in each curve are caused by two
kinds of deformation modes in the Fe-Mn-Si SMA: one shows the critical stress of slip
deformation, and the other shows the critical stress of ε-martensite transformation(FCC→HCP transformation). The critical stress for slip deformation decreases with theincrease of temperature as shown by the broken line in Fig. 1. On the other hand, the criticalstress for ε-martensitic transformation increases with the increase of temperature. That is
to say, the two slopes in Fig. 1 indicate that ε-martensitic transformation preferentiallyoccurs at low temperatures (including the room temperature) and slip deformation occurs at
high temperatures.
Fig.2 shows the change inatomicarrangement

duringstress-induced

martensitic

transformation

from

γ

-austenite(FCC)toε-martensite(HCP). Up to about
20% strain can be introduced
in a specific direction with○:Atoms on the bottom plane

little volume change by thistransformation. As shown in●:Atoms on the one level higher plane from the bottom

Fig.2 Schematic illustration of the ε-martensitic
transformation

Fig. 2, the length of OB after stress-induced transformation is about 23% longer than that of
OA before transformation3). Namely, the stress induced ε-martensitic transformation yields
the shape change without slip deformation. The SME is obtained through reversible
transformation from HCP martensite to FCC parent phase.
In the region of large strain, not only martensitic transformation but also slip deformation
inevitably occurs. Therefore, if the amount of deformation is kept within an appropriate range,
the shape of the material can be changed only by stress-induced martensitic transformation
without causing slip deformation. When the deformation is kept within such a range and thenheated to a temperature at which the γ phase becomes stable, the reverse transformation toγ proceeds while recovering the strain introduced at the time of ε formation. The shapememory effect of Fe-Mn-Si SMA recovers the shape before deformation by this reverse
transformation.
Generally, it is used in a form in which a strain of about 4 to 8% within a range in whichsome slip deformation occurs is applied, and about half to one-third of the applied strain isrecovered as a shape recovery strain.

There are two most importantparameters for utilizing SMA. One
is the shape recovery strain, which
depends on the initial strain andthe number of training cycles, andthe other is the recovery stress.
Therefore, the shape memory
effect of Fe-Mn-Si SMA will be
described separately for strain
and stress.

without training
with training

Recovery strain, m (%)① Shape recovery strain

Recovery ratio,  (%)(3) Shape memory properties

Initial strain, int (%)

First, the shape recovery strainchanges depending on the amountof strain applied and the presence

Fig.3 The relation between initial strain andrecovery strain4)

or absence of training treatment. Fig. 3 shows the relation between initial strain and recovery
strain4). Training treatment consists of repetitive processing of proper deformation andheating2). The results in Fig. 3 are obtained after one cycle of training. Although multicycle
training treatment increases the recovery strain, its effect is saturated gradually.
The recovery strain shows a maximum value with 5~8% initial strain and higher strain
deteriorates its value. On the other hand, the training process is indispensable to restore theshape as close as possible to the state before deformation, and it is limited to the region where
the processing strain is extremely small (2% or less).

② Shape recovery stress
Fe-Mn-Si SMA is generally used as a connecting member. Such applications using
Fe-Mn-Si SMA require recovery stress rather than recovery strain. For example, Fe-Mn-Si
SMA first undergoes tensile deformation and then memorizes its shape (described later). This
shortens the length when heat is applied. Next, if you constrain both ends and apply heat toprevent the material from shrinking, stress will be generated in the fixed parts at both ends.
Fig.4 shows the results of measuring thisstress generated during the shape recovery
process. The solid and dashed lines show
the behavior of recovery stress with andwithout training, respectively5). Since bothshow

similarbehavior,

thetrainedmaterial will be described here as an
example.
Recovering stress begins to generate atabout 50 ℃

(about 100 ° C without

training) and gradually increases until

Fig. 4 Recovery stress vs temperature curve in
the Fe-Mn-Si SMA5)

above 300℃. After heating until about 330℃ (b2) at which the increase of the stress issaturated, the stress further increases by cooling. From this measurement, it can be seen thatthe generated stress includes two stresses, contraction due to shape recovery and contraction
due to cooling after thermal expansion. Since the thermal expansion component acts in the
direction of expanding the fixed parts at both ends in the heating process, the tensile stressshown in Fig. 4 is not a pure shape recovery stress, but a stress in which the contraction force
due to shape recovery overcomes the thermal expansion. The stress increases further whenheated to approximately 330 ° C (point b2) and cooled after the stress has saturated. This
increase in stress is caused by the forces that pull the fixed ends together, turning thermal
expansion into contraction during the cooling process. However, the stress decreases after
reaching the maximum value at point C2, and the stress at point d2 remains when cooled toroom temperature. This stress corresponds to the shape recovery stress that can be used as aconnecting member at room temperature.
In spite of the continuous shrinkage during the cooling process, the stress decreases below
the point c2. This comes from the fact that the temperature at c2 corresponds to the upper
limit of the temperature range for ε-martensitic transformation shown in Fig. 1. Therefore,
below this temperature, stress-induced martensitic transformation can occur again if acertain amount of stress is applied. That is, when the cooling progresses and the temperaturereaches the c2 point or less, the stress accumulated in the material promotes thestress-induced martensitic transformation, and it can be considered that this transformation
relaxes the internal stress. As a result, Fig.4 shows that the available recovery stress is about
200 MPa with training and about 130 MPa without training. However, these values are ideal
ones that do not allow any existence of recovery strain in the process.
In fact, it is difficult to prevent the occurrence of recovery strain completely. The actual stressis less than the ideal value because of the occurrence of recovery strain in general process ofjoining.
Fig. 56) shows an overview of the pipe

SMA joint
形状記憶合金円筒

Pipe
パイプ

Pipe
パイプ

connection method using the SMA joint. The
SMA pipe joint is machined into a ring shape（Ａ）接続する相手パイプとそれより内径が細い形状記憶合金円筒(A) Preparing pipes and a SMA joint*with an inner diameter that is slightly smaller

diameter of this joint to a size that allows the

→
→

→
→

(Fig. 5A). It is made by expanding the inner↑↑than the outer diameter of the connecting pipe

*The diameter of SMA mustbe smaller than pipes（Ｂ）形状記憶合金円筒の拡径(B) Expanding
diameter of a SMA joint

pipe to be inserted at room temperature (Fig.
5B). When pipes are inserted at both ends of
the SMA pipe joint and then the joint part is（Ｃ）形状記憶合金円筒へのパイプ差し込み(C) Inserting pipes into a SMA joint

heated, the inner diameter shrinks due toshape recovery, and the inserted pipes areconnected (Fig. 5C and D).
At this time, if a certain gap is not secured
between the outer diameter of the pipe and the（Ｄ）加熱により形状記憶合金円筒が収縮し接続完了(D) connecting pipes by heating

Fig.5 Connecting pipes with Fe-Mn-Si SMA joint6)

inner diameter of the SMA joint at the stage of Fig.5B, the pipe cannot be inserted into thejoint. On the contrary, if the gap is made too wide, even if the joint contracts due to heating, asufficient tightening force cannot be exhibited. Therefore, it is extremely important to set thesize of the gap appropriately.
This gap corresponds to the distance that the SMA joint contracts freely due to shaperecovery and before it comes into contact with the outer surface of the pipe. It is preferable to
make the gap as narrow as possible in order to give the connecting portion a sufficienttightening force.
Figure 6 shows the shape memory effectdescribed above on the stress-strain diagram.
StressaFirst, in order to use SMA as a joint, deform itin the path of [O → a → b] shown in the figure.
Afterunloading,

2.5~4%

recoverystrainb’ ≒130～
200MPacorresponding to [b → e] is obtained byc’subsequent heating. If there is an obstacle ind’

the direction of the shape recovery at b,
recovery stress corresponding to [b→b’] can beoeattained by heating (130～200 MPa). If some

d

c

b

Strain2.5～4％

interval is present between an obstacle and a

Fig. 6 Schematic diagram of the SME

SMA, the available recovery stress decreases

with the increase of the interval. This is because if the obstacle is at c or d, the shape recovery
occurs along [b→c→c’] or [b→d→d’]. The more recovery strain is consumed, the smaller therecovery stress that can be extracted.
(4) Other fundamental properties
Since Fe-Mn-Si SMA is often
used as a part of large structuralmembers,
required

basic
for

properties

generalsteelmaterials are also important inaddition

to

shape

memoryproperties. Table 27) shows thebasic properties of the materials

Table 2.

Fundamental properties of Fe-Mn-Si SMA7）

Term

Unit

Values

Proof stress
UTS
Ductility
Hardness (Hv)
Density (25℃)
Melting point
Thermal expansion(0～500℃)
Thermal conductivity
Specific heat

MPa
MPa
％
g/cm3
℃

200～300
680～1,000
16～30
190～220
7.2～7.5(7.454)
1,320～1,350℃-1

16.5×10-6

cal/cm･deg･sec
cal/g･deg
Ω･cm

0.02
0.13

after hot working and solution

Specific resistanceheat treatment. Many properties,

Young’s modulus
Shear modulus
Poisson ratio
Ms
Af
Recovery strain
Recovery stress
Magnetic property

such as proof stress and tensile
strength values, as well as theshape of the stress-strain curve,
are similar to SUS304 stainlesssteel.
In case of using SMA, it is

GPa
GPa
℃
℃
％
MPa

100～130×10-6
170.0
65.0
0.359
-20～25130～185
2.5～4.5
150～200
Paramagnetism

indispensable to apply strain in advance. Especially when performing training processing, thedeformation of strain application must be repeated at least twice.
Tungsten inert gas (TIG) or plasma welding are applicable to the Fe-Mn-Si SMA. Further
heat treatment after the welding gives shape memory properties comparable to the parent
materials. It is also possible to bend and form a plate and weld it to make a pipe8). (Currently
no product is manufactured this way) In addition, there was a study that tried to improve theshape memory characteristics by adding a small amount of Nb and V, but currently only
Fe-28Mn-6Si -5Cr with the original composition is manufactured9,10).
(5) How to use Fe-Mn-Si SMA
Fe-Mn-Si SMA material is produced by combinations of hot rolling, cold rolling, forging,drawing, etc. Table 3 shows the basic steps required to use this material.
Table 3. Basic steps for using Fe-Mn-Si SMA
process
Shapememorytreatment
Training
treatment

abstract
Memorize the shape youwant to achieve when you
finally apply heat.
Training enhances recovery
strain and recovery stress.

detailHeating at 950℃ or higher under constraint
after working at room temperature (working
at 950℃ or higher is also effective)
Repeating 4～8% strain and heating at 600℃.
You can repeat it more than once, but theeffect will gradually saturate, so you canrepeat it once or twice.
Deformation Deforms the shape after Deforms near room temperature. Performforshape memory processing
processing methods such as tension,
initial strain
compression, twisting, bending, etc. alone orin combination
Shape
Recovery to the memorized Preferably heated to 350℃ or higher.
recoveryform or obtain recovery Heat the material uniformly so that thetreatment
stresstemperature difference is as small as possible.
The above is the standard process for using Fe-Mn-Si SMA. Of these, the heat treatment
performed in the shape memory processing is basically performed by constraining the shape
to be stored. However, when manufacturing a steel pipe joint by cutting from a round bar, it
may be possible to just heat it without restraint.
(6) Applications of Fe-Mn-Si SMA① Pipe joint for steel pipes
Pipe joint has been considered as the most important application of the Fe-Mn-Si SMA.
While the Ni-Ti SMA had already had good records of application in military-related fields, it
has been considered promising if the inexpensive Fe-Mn-Si SMA can substitute the Ni-Ti
SMA as consumer pipe joints.
However, steel pipes have variations in outside diameter which is allowed in official
standard. This variation is not negligible compared with the magnitude of the shape recovery
strain in Fe-SMAs. Moreover, tensile strength and sealing properties are also required. Even
if the constituent elements have a high cost performance, it is still necessary to spend somemoney to meet these requirements. As a result, the total cost performance was not a sufficientadvantage to substitute the Fe-Mn-Si SMA for conventional pipe joints.

The solution to this problem was suggested as follow. For instance, proper resin coating on
the inner surface of a joint is efficient to improve the sealing property and the strength of thejoint11). Inserting C-rings12) or using screws5) at the interface of pipe and joint was developed
as a method of enhancing the joint strength. Through these processes, the Fe-SMAs were put
into practical use. Some other examples are introduced as below.
A construction method for tunneling work co-called the “curved boring method12)” has beendeveloped. This method is noted as an important technology in tunnel construction in deep
underground areas with unstable ground. Curved steel pipes are laid in the wellbore after
boring outward from the ground, which constitutes a curved pipe roof. Digging of the main
tunnel is conducted under this curved pipe roof. However, the curved steel pipes are too longfor such a narrow work
space. The curved pipes,

After connecting

Before connecting

therefore, must be cut into
Lengthof a SMA joint
ＳＭＡ継手長さ

proper length and inserted
into wellbore at one time.

SMA
joint
ＳＭＡ継手
Pipe
A
鋼管Ａ

Each pipe is jointed withsafetyefficiency

areC-ring SMA joint
Ｃ型リング
ＳＭＡ継手

Pipe B

鋼管Ｂ

Inside of SMA*1
Inside of SMA*2
Inside of pipes
1
Ｓ
Ｓ
Ｓ
Ｓ
鋼
鋼
Outside of
SMA* Outside
Outside of pipesof SMA*2
Ｍ Ｍ
Ｍ Ｍ

the preceding pipe. In thisprocess,widthof a groove
凹溝巾

and

管
外
径

required.

管
内径That is why the Fe-Mn-Si

Ａ
継
手
内
径

Ａ
継
手
外
径

加熱前

Ａ
継
手
外
径

Ａ
継
手
内
径

加熱後

SMA is selected to ensure
the bending and drawing
strength of the joint. As*1Before heating *2After heating

Fig.7
illustrationof Fe-Mn-Si
jointC-ringwith C-ring
Fig.Schematic
8 The schematic
illustrationof a SMASMA
joint with

schematically shown in Fig.
7, the C-ring is inserted
into a ditch formed on the SMA joint and curved pipe13). In this method, the strength at theTable 4.

Relationship between the number of C-rings and the UTS (in 100A steel pipes）14）［Force（kN）］

STPG370 pipe（114.3φ×6.0t）
without C-ringWith a C-ring for each side
With two C-ring for each side
With three C-ring for each side（

2％strain
580(439)
110
430
520
550

Max
789(755)
110
500
580
610

［Ratio respective tothe steel pipe（％）］
2％strainMax
100(100)
100(100)
19( 25)14( 15)74( 98)63( 66)90(118)74( 77)95(125)77( 81)）:Force corresponding to UTS and yield stress as standard lower limit

joint part strongly depends on the number of C-rings. Table 4 shows the result of tensile tests
for 100A SMA pipes. The strength with three C-rings on both sides is comparable to the caseof welding14).

Bending strength is also required to endure soil pressure. The results of 4-point bending
test (with C-ring attached on both sides) shown in Fig. 8 are almost the same as the pipe
without joint14).

100

A鋼管単体（継手無し）
pipe without joint

Through the above experiments,
on a trial basis in 20035). In thiswork, the SMA joint was used for
250A

curvedpipes(outside

diameter 267.3 ㎜φ, bend radiusForce
荷重 (kN)（kN）

the method was actually adopted

形状記憶合金継手で接続した鋼管
Pipeswith SMA joint

50

6000mm in Photo 1). The SMA
joints are produced by centrifugal
casting15) with a composition of
Fe-28%Mn-6Si-5Cr. The joint isheatedbyhigh-frequency

0

0

20

40

60
80
100
120
中央部のたわみ（㎜）Flexure at a central part

140

160

Fig. 8 Results of the 4-point bending test14)

induction heating. This method can be performed by fewer workers in less working hours
compared with welding.

Photo 1. Pipe coupling with Fe-Mn-Si SMA joint

Fish plate for crane rails②

In large factory cranes, gaps in the rail seams can cause local wear on the rail ends, causing
dents and chips. Once a dent or chip occurs, the gap gradually expands, eventually impeding
the running of the crane. The Fe-Mn-Si SMA fishplates were developed to solve this problem.
Generally, rails are connected by applying fish plates on both sides and bolting them
together. Since there is a certain amount of clearance between the bolt hole and the bolt
diameter, even if you try to pull the rails on both sides to fix it, it is inevitable that a gap willbe created due to vibration caused by the movement of the crane. A tight connection of therails can be realized by connecting the tension-deformed Fe-Mn-Si SMA fish plates to the railswith bolts and then shrinking it by heating.16) (Fig. 9).

This fish plate has been used for actual
crane

rail

connection

of

major

steel

SMA joint

manufacturers since the fall of 2004, and SMA
fish plates as shown in Photo 2 are used in a
total of about 2200 locations (As of August2020). In the case of the fish plate shown in
Photo 2, the product weight is about 10 kg(currently about 7 kg), and the on-site heating
to restore the shape of this fish plate uses theflame of the gas burner. The connection timeat one location is about 10 minutes. The gap
between the rail joints is almost completely(1) connecting with bolts
Gap is between rails

eliminated, and the state is maintained for along period of time, so that the traveling of thecrane becomes extremely smooth. Therefore,
it is said that the rail connection by thismethod also contributes to extending the lifeof crane rails, runway garters, and overhead(2) After heating
Gap disappeared.
Fig 9. Rail connection with Fe-Mn-Si SMA

fish platescranes17). It is still in regular use, and noparticular problems have occurred until now,
about 16 years after its practical use.

③

Other applications
Employing the Fe-Mn-Si SMA as joints forframe pipes of bicycle was actually the firstpractical

application

of

this

material17).

Grooves were formed inside of a receiving pipeand outside of an inserting pipe. Contracted
SMA C-rings are set in the grooves of the

Photo 2. Fe-Mn-Si SMA fish plates
for crane rails

inserted pipe. After inserting, the SMA C-ring expands toward the groove of the receiving pipeby heating, which connects the pipes. Since the movement of the C-shaped ring is fixed byinjecting adhesive into the gap between the recesses, it was possible to realize a connectionthat can withstand vibration sufficiently. This method was used on high-end sports bicycles
for about two years, but has since been changed to eliminate the need for SMA rings.
This material is also used for connecting small-diameter and short-diameter ceramic
tubes, which are difficult to make long products19). The pipe (tens of centimeters in length) is
made of Fe-28Mn-6Si-5Cr alloy, and short ceramic pipes are inserted side by side and heated
to restore the shape. Since the ceramic tube is protected by the SMA tube and the entire innersurface is made of ceramics, a structure that is resistant to corrosion and wear from the innersurface and impact from the outside is realized. This application has been put into practicaluse since around 1994 and is still in regular use (as of 2021).
(7) Future prospects and summary
Fe-Mn-Si SMA, which appeared as one of the new materials, has been around 40 years
since the discovery of the material, and more than 30 years have already passed since thestart of development (as of 2021). However, the reality is that full-scale practical use has
finally begun to progress after 2000. At the end of this article, I would like to consider the
background that took such a long time to put into practical use.
The goal of this material at the beginning of its development was to position it as a low-cost
type of Ti-Ni SMA, and to trace the successful application fields of Ti-Ni. From the recognition
that SMA is the Ti-Ni type, it is natural that expectations from the surroundings for Fe-Mn-Si
SMA is in that direction. However, the targets for which expensive Ti-Ni SMAs were put into
practical use were mainly small parts. When trying to utilize Fe-Mn-Si SMA for small parts, it
was a big constraint that the shape recovery strain was small and bidirectional operation was
not possible. It soon became clear that it was impossible to aim for a target similar to the
Ti-Ni SMA simply because of low cost. Against the enthusiastic background of new material
development, several iron-based alloys have emerged, but none of them disappeared from thefront stage when it became clear that they could not replace Ti-Ni SMA. Only Fe-Mn-Si SMA
has continued to make efforts to find a way to develop unique new application fields suitable
for this material. The aim was to put it into practical use as a "structural material with afunction of shape memory effect" as a large structural member, which is difficult for Ti-Ni
SMA. But, while small members can be easily prototyped from laboratory test melt materials,
large members have a series of processes such as melting, forging, hot rolling, cold rolling,
cutting, plastic deformation, and welding. It was required to reexamine the conditions
suitable for this material for the entire manufacturing process. It took more time than
expected in this process, which is one of the reasons why it took so long to put it into practicaluse. It can be said that the current situation is that they have finally begun to bear fruit.
In recent years, it has been discovered that stress-induced martensite in Fe-Mn-Si SMA
returns to the original austenite phase if it is deformed in the opposite direction instead ofheating, which causes superior fatigue durability against repetition of plastic deformation20).
That is, the Fe-Mn-Si alloy has two functions of shape memory effect and fatigue durability.
The representative of the former is the Fe-28Mn-6Si-5Cr alloy described in this paper. On theother hand, the latter is a Fe-15Mn-4Si-10Cr-8Ni alloy whose composition has been adjusted
so that it is suitable for developing fatigue durability and can be mass-produced. The latteralloy can then be manufactured by the continuous casting method22), and has already been
implemented in actual buildings as a maintenance-free steel-based vibration damping
damper core material that can withstand continuous use for a long period of time. The paper24) summarizing from the beginning of the development of Fe-Mn-Si SMA to new applications

as a steel vibration damper is often cited, and due to its influence, the papers about Fe-Mn-Si
SMA written 30 years ago 2) 3) are also often quoted. This indicates that research on

stress-induced transformation of Fe-Mn-Si alloys, which began in the early 1980s, is once
again receiving worldwide attention.
In the world of SMA, Fe-Mn-Si alloys have survived by finding unique applications such as
crane rail joint plates for applications different from Ti-Ni alloys. Thanks to that, in recent
years, we have come across new features with excellent fatigue resistance. In the future,
although the fields and scales will be different, we would like to move forward strongly with
two applications, shape memory applications and fatigue endurance applications.
(Revised in February 2021)
References
1) A.Sato, E.Chishima, K.Soma and T.Mori：Acta Metall., 30 (1982)1177
2) H.Otsuka, M.Murakami and S.Matsuda：Proc. of MRS Int. Mtg. on Advanced
Materials, 9 (1989)451
3) H.Otsuka, H.Yamada, T.Maruyama, S.Matsuda, H.Tanahashi and M.Maruyama: ISIJ International 30 No.8(1990) 674
4) H.Naoi and T.Maruyama：Journal of the JSTP，45 (2004)697
5) H.Tanahashi,T.Maruyama and H.Kubo：Trns. Mat. Res. Soc. Jpn. 18B (1993)1149
6）H.Kubo and T.Maruyama：Densizairyo，No.4 (2002)56
7）T.Maruyama and T.Kurita：Kinzoku，74 (2004)160
8）T.Maruyama and H.Otsuka：Kinzoku，66 (1996)1079
9）S.Kajiwara，D.Liu，T.Kikuchi and N.Shinya：Scripta Mater. 30 (2001) 2809
10） H.Kubo，K.Nakamura，S.Farjami and T.Maruyama：6th. ESOMT，Cirencester，Engrand，／Materials Science and Engineering-Lausanne-A：378 (2004) 343
11）H.Yamada, T.Maruyama, H.Otsuka and H.Tanahashi：Yousetsu Gijyutsu，No.9 (1988) 79
12 ） T.Kasuya, T.Obata, H.Miki and T.Maruyama ： Proceeding of the Symposium on
Underground Space（JSCE），5 (2000) 163
13）Y.Kameoka and T.Kasuya：JSCE Magazine，No.4 (1995) 36
14 ） T.Kasuya, T.Obata, H.Miki and T.Maruyama ： Proceeding of the Symposium on
Underground Space（JSCE），7 (2002) 371
15）H.Otsuka，T.Maruyama and H.Kubo：Mat. Sci. Forum 327-328 (2000) 243
16）T.Toyozawa, S.Kozaki and K.Ando：Kuren，45 No.4 (2007) 1
17) H.Tsujimoto, S.Kozaki, K.Okutani, T.Tomizawa, K.Ando, S.Yorimitsu, N.Matsuishi and
H.Ishii：Kuren, 56 No.4 (2018) 4
18）H.Otsuka：Kinzoku, 60 No.3 (1990)29
19）T.Aoki, K.Fukuda, H.Matsuoka, A.Nobumoto, N.Matsumoto, A.Oshio, H.Taira：
Zairyou-to-Purosesu, 7 No.1(1994) 29
20）T.Sawaguchi, P.Sahu, T.Kikuchi, K.Ogawa, K.Kushibe, M.Higashino and T.Ogawa：Scripta
Mater., 54 (2006)1885
21）T.Sawaguchi, T.Maruyama, A.Kushibe and K.Tsuzaki：Yosetsu-gijutsu 63 No.6 (2015) 77
22）H.Otsuka, Y.Chiba, T.Sawaguchi, S.Takamori, A.Kushibe, K.Umemura and Y.Inoue：FallMeeting of the Japan Institute of Metals 2018 J76
23) A.Kushibe, K.Umemura, Y.Inoue, T.Nakamura, T.Sawaguchi, H.Otsuka and Y.Chiba：
Yosetsu-gijutsu 68 No.2(2020)60
24) T.Sawaguchi, T.Maruyama, H.Otsuka, A.Kushibe, Y.Inoue and K.Tsuzaki ：Materials
Transactions, Special Issue on New Aspects of Martensitic Transformations 57
No.3(2016)283