Abstract
In order to make an equiatomic TiNi having the same density as that in the melting ingot by means of powder metallurgy, sintering characteristics of binary blended elemental compacts were investigated primarily and the sintering condition to obtain single phase of TiNi was determined. The density ratio of the TiNi obtained, however, was around 85%. In the next step, the effect of high pressure treatment in which from 203 to 810 MPa of hydrostatic pressure is applied at 1213K for 3.6ks on the density was examined.
Followings are the results obtained:
1) When the titanium powder of - 150 mesh size and carbonyl nickel powder ranging from 3 to 7μm were used as starting materials, single phase of TiNi can be obtained by the sintering in vacuum at 1273K for 36ks.
2) Density of the TiNi can be improved markedly by the high pressure treatment of over 203MPa of hydrostatic pressure and the density ratio reached almost 100%.
3) Diffusion rate between Ti and Ni particle in the blended elemental compacts under hydrostatic pressure was slower than that in vacuum.
4) The oxygen content of the TiNi sintered compact having 100% of density ratio was 0.27 wt% and the martensitic transformation started at 247K.
