Weakening Mechanisms of Platelike σ Phase on Ni-base Superalloys
摘要
On the basis of an investigation on σ phase inNi-base cast superalloy K24 and the results aboutσ phase in other Ni-base superalloys,an embrittl-ing mechanism and a softening mechanism,bywhich platelike σ phase weakens the Ni-basesuperalloys,have been proposed.It is consideredthat the platelike morphology and the habit precipi-tation along{111}of σ phase are necessary condi-tions for both mechanisms.The embrittling mecha-nism is dominant at room temperature and highstrain rate,and the softening mechanism is domi-nant at high temperature and low strain rate.Ac-cording to the idea of the softening mechanism andthe analyses of σ phase and alloy compositions,it isconsidered that Nb,Mo and W in the alloys may beresistant to the detrimental effect of σ phase on thestress-rupture properties of the alloys.