Zr,Cr和B对Ni_3Al合金组织和力学性能的影响

EFFECT OF Zr, Cr AND B ADDITIVES ON MICROSTRUCTURE AND MECHANICAL PROPERTIES OF Ni_3 Al ALLOYS

本文研究了含Zr(0—0.6at.-%),Cr(0—7.7at.-%)和B(0—2.22at.-%)的Ni_3Al合金的组织和室温至1050℃拉伸性能。结果表明,Ni_3Al合金的屈服强度随温度升高而增加,表现出反常的温度关系。到达峰值后,随温度升高,屈服强度降低。Zr和Zr+Cr在整个试验温度范围都增加Ni_3Al合金的屈服强度,并改善高温抗张强度和塑性。硼增加Ni_3Al合金的抗张强度和屈服强度,同时改善塑性。但当硼含量超过1.37at.-%时,则降低强度和塑性。当硼含量超过溶解度极限时,Ni_3Al合金中形成岛状和球状的Ni_(20)Al_3B_6和Ni_3Al的共晶组织,对强度和塑性都是有害的。

The microstructure and the mechanical properties from room temper-ature up to 1050℃ of Ni_3Al base alloys containing 0--0.6 at.-%Zr, 0--7.7 at.-%Crand 0--2.22 at.-%B have been investigated. It was found that the temperature depen-dence of their yield strength variation reveals to be anomalous, i. e., the strengthincreases with the elevating of temperature, and thence decreases till it surpassedthe peak value. Both Zr and Zr + Cr may improve the yield strength of thealloys in the entire range or testing temperatures, as well as the tensile strengthand elongation under high temperature. B is favourable to raise the tensile andyield strength of the alloys, and also the plasticity. But the strength will reduce asB added over 1.37 at.-%. The Ni_(20)Al_3B_6 and Ni_3Al eutectic mixture like islandsand globes precipitated inside grain and along grain boundaries, which are harmfulto the strength and ductility, may be formed when the B content exceeds the limitof solubility.