Jason Subirana

The effect of aging treatments on the microstructure, martensite transformation temperature and shape memory effects (SME) of the Ni46Ti44Ta10 alloy was carefully studied in this work. The result show that the microstructure of Ni46Ti44Ta10 alloy contains an NiTi phase, a eutectic structure, which formed by NiTi, and (beta) -Ta phase, and some dispersed NiTa2 compound. The aging treatment can produce Ti11Ni14 precipitates in the alloy. Meanwhile, precipitation hardening was noticed during the… Show more

The effect of aging treatments on the microstructure, martensite transformation temperature and shape memory effects (SME) of the Ni46Ti44Ta10 alloy was carefully studied in this work. The result show that the microstructure of Ni46Ti44Ta10 alloy contains an NiTi phase, a eutectic structure, which formed by NiTi, and (beta) -Ta phase, and some dispersed NiTa2 compound. The aging treatment can produce Ti11Ni14 precipitates in the alloy. Meanwhile, precipitation hardening was noticed during the aging process. The phase transformation temperatures and hardness of the sample alloy vary with the changing of the composition and redistribution of each phase during the aging treatments. After the aging treatment, the samples demonstrated an enhanced shape memory effect compared with untreated samples. It is also evident that there is a strong correspondence between the enhanced shape memory effect and the increase of the hardness value. Show less

This paper studies the effect of Ta addition on the martensitic transformation characteristics and the X-ray visibility of NiTi shape memory alloys. It was found that: (1) The transformation temperatures of the Ti49Ni51 binary alloy increase drastically by an addition of 0 -- 4at%Ta, but only slightly when the concentration exceeds 4at%. (2) The addition of Ta greatly decreases the sensitivity of the martensitic transformations to the variation in the Ni-Ti ratio. (3) The addition of Ta to a… Show more

This paper studies the effect of Ta addition on the martensitic transformation characteristics and the X-ray visibility of NiTi shape memory alloys. It was found that: (1) The transformation temperatures of the Ti49Ni51 binary alloy increase drastically by an addition of 0 -- 4at%Ta, but only slightly when the concentration exceeds 4at%. (2) The addition of Ta greatly decreases the sensitivity of the martensitic transformations to the variation in the Ni-Ti ratio. (3) The addition of Ta to a TiNi binary alloy can improve its X-ray visibility Show less