In order to develop new functional biomaterials, the Zr Au alloy system was focused and a Zr 9 molAu near eutectoid alloy was used in this work. Effect of solution treatment and aging treatment temperatures on phase constituent, microstructure and Vickers hardness was investigated. It was found that Zr 9 molAu is a hypereutectic composition and experimental results in this work are not in agreement with the experimental phase diagram reported by Lomello Tafin et al., but in good agreement with the calculated phase diagram reported Su et al. The major apparent phase was hcp aZr regardless of the heat treatment condition and Zr 3 Au second phase precipitated when heat treated at 1173 K or lower temperatrues. The Vickers hardness value was HV503 after the solution treatment at 1273 K, but became lower with increasing the amount of micrometer size Zr 3 Au precipitates. The hardness of this alloy was mainly due to the amount of the solute Au in aZr matrix. However, the alloy was slightly hardened by aging at 673 K due to the formation of submicron meter size fine Zr 3 Au precipitates.

Although AuCuAl shape memory alloys are hopeful as advanced functional biomaterials exhibiting shape memory effect and good X ray radiography, the limited ductility in polycrystalline materials is a drawback for practical applications. In this study, effects of quaternary elements (B, Ti, Zr, Cr, Mn, Fe, Zn, In and Sn) on martensitic transformation start temperature (M s ) and mechanical properties are investigated. It was found that (1) Mn, Fe, In and Sn additions decrease M s and that (2) B, Ti, Zr, Cr and Zr additions do not affect or slightly increase M s . Among the quaternary additions investigated, only Fe addition drastically improves ductility. Therefore, Fe is concluded to be the effective additional element to bring both sufficiently low M s and ductility to AuCuAl alloys.

Recently, the Ti-Zr-Nb alloys have been developed as Ni-free shape memory and superelastic alloys. In this study, the effects of Nb and nitrogen (N) contents on martensitic transformation behavior, shape memory effect and superelasticity in Ti-18Zr-(12$16)Nb-(0$1:0)N (at%) alloys are investigated using loading and unloading tensile tests, optical microscopy and X-ray diffractometry. The shape memory effect is observed in Ti-18Zr-(12$13)Nb and Ti-18Zr-12Nb-0.5N alloys at room temperature. The superelastic behavior appears by the increase of Nb or N content. The Ti-18Zr-(14$15)Nb, Ti-18Zr-(13$14)Nb-0.5N and Ti-18Zr-(12$14)Nb-1.0N alloys exhibit the superelasticity at room temperature. The martensitic transformation start temperature decreases by 75 K with 1 at% increase of N content for the Ti-18Zr-13Nb alloy. The critical stress for slip deformation and the stress for inducing the martensitic transformation increase with increasing N content. The superelastic recovery strain is also increased by adding N. The maximum recovery strain of 5.0% is obtained in the Ti-18Zr-14Nb-0.5N alloy.

The effect of annealing temperature on texture formation associated with superelastic behavior is clarified of Ti 4Au 5Cr 8Zr biomedical alloy in which Ti 3 Au precipitates at 973 K and 1073 K but does not precipitate at 1173 K. A Ti 4Au 5Cr 8Zr alloy ingot was cold rolled with a reduction up to 98 in thickness followed by annealing at 973, 1073 and 1173 K for 1.8 ks. It was found that the as rolled alloy and the alloy annealed at 973 K exhibit {112} b 〈110〉 b rolling texture, while the alloys annealed at 1073 K and 1173 K exhibit {001} b 〈110〉 b recrystallization texture regardless of Ti 3 Au precipitates. {001} b 〈110〉 b texture develops stronger in the alloy annealed at 1173 K compare with the alloy annealed at 1073 K. This is one of the reasons why alloy annealed at 1173 K shows larger shape recovery strain than the alloy annealed at 1073 K when tensile strain is applied along the rolling direction.