Development and dental casting of the super-elastic alloy with superior biocompatibility

在所有形状记忆合金中，钛镍合金表现出优异的功能性能。然而，镍(Ni)从这种合金中的少量溶解是生物相容性的问题。研究了用钯(Pd)、铜(Cu)和金(Au)等第三种元素取代镍，以减少具有形状记忆效应和超弹性的钛镍合金中镍离子的释放。添加7.5%(质量%)的钯使钛镍合金表现出挠性超弹性，与二元超弹性钛镍合金相比，表现出约一半的表观应力(0.2%)。随着铜替代量的增加，合金的表观证明应力和残余应变均降低。此外，在二元形状记忆钛镍合金中加入铜还可以获得更大的超弹性范围。添加10%铜的二元钛镍合金是一种很有前途的体温超弹性成分，在310K下1%乳酸的浸泡实验中，镍离子释放较少。随着Au掺杂量的增加，相变温度下降到Au加入量为7%时，DSC测试结果表明，当Au加入量为7%时，相变温度基本不变。49.4%Ti-Ni-4%Au和49.6%Ti-Ni-7%Au合金在体温下表现出超弹性。此外，在添加10%铜的钛镍合金中添加0.5%的钼或铬似乎是与力学性能有关的极限，因为添加1.0%或更多的钼或铬会导致合金的脆性。

Ti-Ni alloy exhibits superior functional property among all shape memory alloys. Nevertheless, a small amount of dissolution of nickel (Ni) from this alloy concerns biocompatibility. In this study, the substitution of the third elements such as palladium (Pd), copper (Cu) and gold (Au), for Ni was investigated to decrease Ni ion release from Ti-Ni alloy which possesses shape memory effect and super-elasticity.Pd addition of 7.5% (mass%) to Ti-50.0Ni alloy showed flexible super-elasticity, which exhibited approximately a half apparent (0.2%) proof stress comparing with the binary super-elastic Ti-Ni alloy. With the increase of Cu substitution, both the lower apparent proof stress and residual strain were observed. Moreover, enlarged content of super-elastic range was obtained by Cu addition to binary shape memory Ti-Ni alloy. 10% Cu addition of binary Ti-Ni alloy was promising composition of super-elasticity at body temperature, and exhibited less Ni ion release in the result of immersion test of the 1% lactic acid at 310K. With the increase of Au substitution, transformation temperatures decreased up to the 7% Au addition and indistinguishable in the further addition by DSC measurement. 49.4%Ti-Ni-4%Au and 49.6%Ti-Ni-7%Au alloy were proved to show super-elasticity at body temperature. Furthermore, 0.5 mass% Mo or Cr addition to the 10% Cu added Ti-Ni alloy seemed the limit in relation to mechanical properties since 1.0 mass% or more addition of Mo or Cr to the alloy showed brittleness.