TY - JOUR
T1 - Effect of Nb addition on martensitic transformation behavior of AuTi-15Co based biomedical shape memory alloys
AU - Shim, Hyunbo
AU - Tahara, Masaki
AU - Inamua, Tomonari
AU - Goto, Kenji
AU - Yamabe-Mitarai, Yoko
AU - Hosoda, Hideki
N1 - Publisher Copyright:
© 2015 The Japan Institute of Metals and Materials.
PY - 2015
Y1 - 2015
N2 - The effect of quaternary addition of Nb being from 0 to 2 mol% on the phase constitution, phase transformation behavior and shape memory behavior of Au-50 mol%Ti-15 mol%Co (AuTiCo) alloys is studied. X-ray diffraction analysis shows that, with increasing Nb concentration, the primary phase appeared at room temperature changes from B19 orthorhombic martensite phase to B2 cubic parent phase, and that all the lattice parameters are not largely changed by Nb addition. The maximum transformation strain evaluated in 2 mol%Nb-added AuTiCo is 7.4%. Differential scanning calorimetry revealed that the reverse martensitic transformation finish temperature (Af ) decreases from 414K in Nb-free AuTiCo to 303K by 2 mol%Nb addition. The ratio of Af change by Nb addition is evaluated to be -55K/mol%Nb, that is comparably larger than -31K/mol%Nb in NiTi. These results indicate that Nb addition is effective to stabilize B2 parent phase. AuTiCo alloy containing less than 2 mol%Nb exhibits shape memory effect with 90% shape recovery ratio. Besides, AuTiCo containing 2 mol%Nb exhibits 2.8% superelastic shape recovery at room temperature as well as 7.4% maximum transformation strain. Therefore, Nb addition to AuTiCo is effective to decrease the martensitic transformation temperature and to improve superelasticity, although the transformation temperature hysteresis increases by Nb addition, similar to Nb-added NiTi.
AB - The effect of quaternary addition of Nb being from 0 to 2 mol% on the phase constitution, phase transformation behavior and shape memory behavior of Au-50 mol%Ti-15 mol%Co (AuTiCo) alloys is studied. X-ray diffraction analysis shows that, with increasing Nb concentration, the primary phase appeared at room temperature changes from B19 orthorhombic martensite phase to B2 cubic parent phase, and that all the lattice parameters are not largely changed by Nb addition. The maximum transformation strain evaluated in 2 mol%Nb-added AuTiCo is 7.4%. Differential scanning calorimetry revealed that the reverse martensitic transformation finish temperature (Af ) decreases from 414K in Nb-free AuTiCo to 303K by 2 mol%Nb addition. The ratio of Af change by Nb addition is evaluated to be -55K/mol%Nb, that is comparably larger than -31K/mol%Nb in NiTi. These results indicate that Nb addition is effective to stabilize B2 parent phase. AuTiCo alloy containing less than 2 mol%Nb exhibits shape memory effect with 90% shape recovery ratio. Besides, AuTiCo containing 2 mol%Nb exhibits 2.8% superelastic shape recovery at room temperature as well as 7.4% maximum transformation strain. Therefore, Nb addition to AuTiCo is effective to decrease the martensitic transformation temperature and to improve superelasticity, although the transformation temperature hysteresis increases by Nb addition, similar to Nb-added NiTi.
KW - AuTiCo
KW - Biomedical shape memory alloys
KW - Martensitic transformation behavior
KW - Niobium addition
KW - Shape memory effect
KW - Superelasticity
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U2 - 10.2320/matertrans.M2014418
DO - 10.2320/matertrans.M2014418
M3 - Article
AN - SCOPUS:84923805634
VL - 56
SP - 429
EP - 434
JO - Materials Transactions
JF - Materials Transactions
SN - 1345-9678
IS - 3
ER -