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

Ti-Ni合金在所有形状记忆合金中表现出优异的功能性能。然而，少量镍（Ni）从该合金的溶解关系到生物相容性。本文研究了用钯（Pd）、铜（Cu）和金（Au）等第三元素取代Ni，以减少具有形状记忆效应和超弹性的Ti-Ni合金中Ni离子的释放。当Pd添加量为7.5%（质量%）时，ti -50.0 - ni合金表现出柔性超弹性，与二元超弹性Ti-Ni合金相比，其表观抗应力约为一半（0.2%）。随着Cu取代量的增加，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Ti-Ni合金中加入Cu可以扩大合金的超弹性范围。添加10% Cu的二元Ti-Ni合金具有较好的体温超弹性成分，在310K下1%乳酸浸泡试验中，Ni离子释放量较少。随着Au取代量的增加，在Au添加量为7%时，转变温度下降，DSC测量表明，在Au添加量进一步增加时，转变温度无法区分。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% Cu的Ti-Ni合金中添加0.5质量% Mo或Cr似乎是力学性能的极限，因为添加1.0质量%或更多Mo或Cr的合金表现出脆性。

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.