The characteristics of age
hardening were studied for Fe W Co and Fe W Co Ni alloys.The results indicated that two kinds
of alloys all possess intensive ablity of age hardening.The rate of hardening of Fe W Co Ni alloy is higher than that of Fe W Co alloy at lower temperature.Accompanying a rise in temperature the rate of hardening of Fe W Co alloy rose rapidly.The hardness was raised to 64HRC from 47HRC of quenching state when ageing at 630℃ for 10min only for Fe W Co alloy. Microstructural characteristics of quenching and ageing were determined by transmission electron microscopy(TEM) and by X ray diffraction(XRD).Results showed that a
modulation structure forms at first stage of ageing,which is completely coherent with matrix and caused strong coherent stress.It is this modulation structure that caused quickly ageing hardening.The precipitation of Fe W Co alloy is more disperse and smaller than that of Fe W Co Ni alloys at 570℃ ageing for two hours.This is the reason why Fe W Co alloy possesses stronger ability of age hardening.