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The methods of XRD, TEM and energy dispersive X-ray (EDX) were used to investigate the pre cipitation process in Ni47Ti44Nb9 specimens annealed at 850℃. A diffusional transformation took place when the al loy was subjected to a long time heat treatment, most of β-Nb particles disappeared and a new precipitate ( N1,Nb);Ti with an h.c.p. structure (a=0.512 2 nm, c = 0.8376nm, and c/a= 1.63) was found, which was similar to Ni3Ti in structure. The upper critical precipitation temperature of the alloy was above 950℃ It meant that the presence 01 niobium inhibited the occurance of the precipitation. In addition, the orientation relationship between the remaining β-Nb precipitate and matrix was observed: [111] β-Nb//[111]M, (110)β-Nb//(110)M.
The methods of XRD, TEM and energy dispersive X-ray (EDX) were used to investigate the pre cipitation process in Ni47Ti44Nb9 specimens annealed at 850 ° C. A diffusional transformation took place when the al loy was subjected to a long time heat treatment, most of β-Nb particles disappeared and a new precipitate (N1, Nb); Ti with an hcp structure (a = 0.512 2 nm, c = 0.8376 nm, and c / a = 1.63) was found, which was similar to Ni3Ti in structure The upper critical precipitation temperature of the alloy was above 950 ° C. It means that the presence of 01 niobium inhibited the occurance of the precipitation. [111] β- Nb // [111] M, (110) β-Nb // (110) M.