| Microstructural characteristics of Ti_(50)Ni_(50-x)Fe_x(x=0, 1, 2, 5 at%) processed by self-propagating high temperature synthesis method(SHS method) have been investigated in the present study. Ti_(50)Ni_(50-x)Fe_x(x=0, 1, 2, 5) processed by SHS method consists of TiNi and NiTi₂. Amount of NiTi₂ increases with increase of Fe content. The TiNi phase has an intermediate phase structure which exhibits extra reflections in the electron diffraction patterns. Therefore, high temperature B2 structure transforms into the intermediate phase structure during SHS processing. Several types of extra reflections such as 1/2<1 0 0>, 1/2<1 1 0>, 1/4<2 1 0> are superimposed on the B2 structure reflections. The transformation into the intermediate phase structure results in the formation of 50∼200 ㎚ scale microdomain structure in TiNi phase. The transformation into the intermediate structure occurs at lower temperature with heat treatment at high temperature or with increasing Fe content. Thus, no intermediate structure phases are observed after heat treatment at 900℃ for 7 hours. |
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