日本金属学会誌

J. Japan Inst. Metals, Vol. 28, No. 2 (1964),
pp. 72-78

On the Temper Hardening Properties of Co-W Alloys

Tadatoshi Toda1

1Hitachi Research Laboratory, Hitachi, Ltd., Hitachi

Abstract:

Rods of Co-W (0∼ 25%) alloys were made by sintering and hot swaging. Dilation behaviors through the α β 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 the tempering of quenched specimen at 600°∼ 675°C, retained β -phase transforms slowly into the h.c.p. lattice of α -phase accompanying the increase in hardness. The rate of the 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 the metallographic method. The nose of the T.T.T. diagram is placed at about 750°C, where the beginning or the ending time of the transformation is equal to about 700 sec or 10,000 sec respectively.


(Received 1963/9/5)

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