抄録
Rods of Co-W (0∼25%) alloys were made by sintering and hot swaging. Dilatation behaviors through the α\
ightleftarrowsβ transformation and X-ray diffraction analyses of quenched or tempered specimens were examined for these alloys. The temper hardening and the T.T.T. diagram of the β-to-α transformation were measured in detail for Co-25% W alloys. The results obtained are concluded as follows: (1) The crystal structure of Co-25% W alloy quenched from 1100°C has the f.c.c. lattice of β phase. (2) Upon tempering of the quenched specimen at 600∼675°C, the retained β-phase transforms slowly into the h.c.p. lattice of α-phase accompanied by an increase in hardness. The rate of transformation is apparently controlled by diffusion. The maximum Vicker’s hardness value, 750, is attainable by optimum conditions of the tempering. (3) The T.T.T. diagram of the β-to-α transformation was determined in Co-25% W alloy by a metallographic method. The nose of the T.T.T. diagram is placed at about 750°C, where the beginning and the ending times of the transformation are about 700 sec and 10,000 sec respectively.
