Shape-memory alloy

Shape memory alloy(KIOKALLOY) excels in high-strength, corrosion resistance

KIOKALLOY, a Ni-Ti alloy, is superior for various reasons such as its strength and corrosion resistance. KIOKALLOY has been born out of Daido’s abundance of experience in working with special steel and high-purifying materials through original processes such as our melting furnace and vacuum arc furnace.

Features

  • It can be set at a wide range of “recovery temperature”. (10℃~100℃)
  • Its corrosion resistance is the same as titanium and titanium alloy.
  • Its tensile strength is about 150kgf/mm2.
  • Its super elasticity effect means that large distortions are easily corrected. Up to 8% of its shape can be recovered in the temperature zone beyond the shape recovery temperature.

Applications

Shape-memory effect
Super-elasticity effect
Pipe joint(radioactive waste transport pipe)
Wire (brassiere, corset, drool bib for baby, frame of hat)
Dental root (inserted into the bone and fixed)
Frame of glasses
Electrical connector(Utilization of temperature up of inferior contact point)
Teeth-straightening(crownwork, arch wire)
Automatic closing mechanism of window
Catheter lead wire for introducing X-ray contrast medium (follow flexibly in vessel)
Air conditioner sensor flap
Rehabilitation apparatus for forming
Spring cellar
Antifreezing valve (turn the faucet on lowering temperature)  
Fan clutch (stop operation at low temperature)  
Temperature alarm (alternative bimetal)  
Medical implant (expanding vessel)  

Chemical composition and shape-recovery temperature

Item Ni Ti Co Cu Shape-recovery temperature
Ni-Ti alloy
 (KIOKALLOY-R)
54~56
Residual Bal.
-
-
20~100℃
Ni-Ti-Co alloy
 (KIOKALLOY-S)
53~55
Residual Bal.
1~3
-
-30~30℃
Ni-Ti-Cu alloy
 (KIOKALLOY-T)
47~50
Residual Bal.
-
5~9
40~70℃
  • Shape-recovery temperature varies depending on forming and heat treatment conditions.

Mechanical properties

Item Ni-Ti alloy Ni-Ti-Co alloy Ni-Ti-Cu alloy
Martensitic phase Tensile strength MPa
(kgf/mm2)
1175~1370
(120~140)
1370~1570
(140~160)
1175~1765
(120~180)
Yield strength MPa
(kgf/mm2)
~196
(~20)
~294
(~30)
68~98
(7~10)
Elongation % ~50 ~50 ~20
Horizontal modulus of elasticity MPa
(kgf/mm2)
7845~9800
(800~1000)
9800~13730
(1000~1400)
0~4900
(0~500)
Martensitic phase Tensile strength MPa
(kgf/mm2)
1075~1175
(110~120)
1275~1370
(130~140)
1175~1765
(120~180)
Yield strength MPa
(kgf/mm2)
390~785
(40~80)
490~980
(50~100)
390~785
(40~80)
Elongation % ~20 ~20 ~20
Horizontal modulus of elasticity MPa
(kgf/mm2)
17650~21575
(1800~2200)
25500~28440
(2600~2900)
19615~27460
(2000~2800)
  • Mechanical properties vary depending on heat treatment conditions and service temperatures.

Comparison of physical properties

Metal Density
(g/cm3)
Melting point
(℃)
Linear expansion coefficient
(×10-6/K)
Specific heat
(J/(kg・K))
Thermal conductivity
(W/m/℃)
Electric resistance
(Ωm)
Ni-Ti
(Austenitic phase)
6.5

1250
~1280

10
440
12.1
80~100
Ni-Ti-Co
(Austenitic phase)
6.5
1250
~1280
-
470
12.7
-
Ni-Ti-Cu
(Austenitic phase)
6.4
1250
~1280
-
460
13.5
-
Titanium
4.5
1668
8.4
520
17.1
55
Nickel
8.9
1453
15
460
92.0
9.5
Iron
7.9
1530
12
460
62.8
9.7
SUS304
7.7
1400
~1420
17
500
16.3
72
Copper
8.89
1083
17
380
385.0
1.724
  • Physical properties, except for density and melting point of Ni-Ti alloy vary depending on temperature.
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