【摘要】 研究了Y,Ce对含铪(Hf)镍基铸造高温合金K444返回料(添加50%返回料)合金的力学性能和组织的影响。研究结果表明:适量Y,Ce(Y<0.03%,Ce<0.015%(质量分数))添加到返回料合金后,一方面,Y,Ce具有去除N,O等有害杂质的作用,使O含量由15×10-6降低到8×10-6,N含量由35×10-6降低到18×10-6,从而使返回料合金得到净化。另一方面,Y,Ce细化了枝晶组织,减少了共晶和大块状碳化物数量,并且强化了晶界。和未加Y,Ce的返回料合金相比,添加Y,Ce使返回料合金室温拉伸强度提高约100 MPa,塑性提高近一倍;使900℃的高温瞬时拉伸性能波动较为平稳,塑性提高近一倍。添加Y,Ce还可以提高返回合金900℃/274 MPa条件下的持久性能,达到新料水平;可以明显延长K444返回合金900℃/274 MPa条件下的蠕变第二阶段,提高蠕变寿命。更多还原

【Abstract】 The effects of Y and Ce doping on the microstructure and mechanical properties of a revert Hf contained nickel base superalloy K444(with 50% revert alloy) were investigated.The results showed that an appropriate addition of Y and Ce(Y<0.03%,Ce<0.015%) in the revert alloy could reduce the harmful impurity O from 15×10-6 to 8×10-6 and N from 35×10-6 to 18×10-6,and consequently purify the revert alloy.On the other hand,Y and Ce led to fine dendrites,decreased eutectics and block carbides,and strengthened grain boundary.Compared with the revert alloy without Y and Ce,the Y and Ce doped alloy possessed 100 MPa higher tensile strength and double tensile ductility at room temperature.While at 900 ℃ the variation of tensile ductility of the Y and Ce doped revert alloy was slighter,and the tensile ductility doubled that of the revert alloy without Y and Ce.With Y and Ce doping,the stress-rupture life of the revert alloy at 900 ℃/274 MPa was prolonged and approached to that of virgin alloy.In addition,the secondary stage during creep at 900 ℃/274 MPa was prolonged and thus the creep rupture was improved.更多还原