H. Tobe, H. Y. Kim, S. Miyazaki, University of Tsukuba, Tsukuba, Japan; H. Hosoda, Tokyo Institute of Technology, Yokohama, Japan
Recently, many Ti-Nb base alloys have been developed as allergy free biomedical superelastic materials. However, a small transformation strain is one of the major problems of Ti-Nb base superelastic alloys. Our research group has suggested that the addition of Zr as a substitute of Nb is effective to increase the transformation strain of Ti base superelastic alloys. It has been reported that the strong texture is developed during thermo-mechanical process and superelastic properties can be improved by texture control in the Ti-Nb base alloys. In this study, the effect of Nb content on deformation and recrystallization textures of Ti-18Zr-Nb alloys was investigated. Ti-18Zr-(12-18)at.%Nb alloy ingots were fabricated by an Ar arc melting method and then homogenized at 1273K for 7.2ks in vacuum. The ingots were cold rolled with a reduction up to 99% in thickness. The as-rolled plates were heat treated at 1173K for 1.8ks in an Ar atmosphere. For the as-rolled specimens, a very weak texture was observed in the Ti-18Zr-(12-17)Nb alloys, whereas a well developed {001}<110> texture was confirmed in the Ti-18Zr-18Nb alloy. Recrystallization occurred in the specimens heat treated at 1173K for 1.8ks. The recrystallization texture was dependent on Nb content. Strong {001}<110>, {111}<110> and {112}<110> recrystallization textures were observed in the Ti-18Zr-(12-16)Nb, Ti-18Zr-17Nb and Ti-18Zr-18Nb alloys, respectively.
Summary: Recently, many Ti-Nb base alloys have been developed as allergy free biomedical superelastic materials. However, a small transformation strain is one of the major problems of Ti-Nb base superelastic alloys. Our research group has suggested that the addition of Zr as a substitute of Nb is effective to increase the transformation strain of Ti base superelastic alloys. It has been reported that the strong texture is developed during thermo-mechanical process and superelastic properties can be improved by texture control in the Ti-Nb base alloys. In this study, the effect of Nb content on deformation and recrystallization textures of Ti-18Zr-Nb alloys was investigated.
