微量磷(P)对等原子比NiAl的微观组织与力学性能的影响

研究了微量P对挤压态等原子比NiAl的微观组织与高温力学性能的影响.结果表明:微量P的添加对NiAl的晶格常数有一定的影响,P偏聚于NiAl晶界处;并对其高温延伸率有重要影响.P偏聚于晶界阻碍了合金变形过程中的动态回复和再结晶,加剧了晶界处孔洞的形成,造成了NiAl-P合金与二元NiAl合金高温力学性能的显著差异,主要表现在:应力-应变曲线经历了较长的加工硬化阶段;最大延伸率明显下降;变形激活能升高,应变速率敏感指数下降.NiAl-P合金的高温变形机制为变形过程中位错的滑移与攀移共同作用.

Effect of Trace Element P on Microstructure and Mechanical Properties for Stoichiometric NiAl

The effect of trace element P on the microstructure and mechanical properties at high temperature for stoichiometric NiAl as extruded were investigated.The results showed that the little doping P mainly segregated at the grain boundaries and influenced the lattice parameter of NiAl and the elongation at high temperature.The segregation of P at the grain boundaries impeded the process of dynamic recovery or recrystallization during deformation at high temperature,which aggravated to the formation of cavities at the grain boundaries and this made the different mechanical properties between pure stoichiometric NiAl with and without phosphorus.The difference mainly revealed as follow:(1)the alloy doping little P experienced long time hardening in the true-stress vs true strain curves;(2)the largest elongation was decreasing during the deforming process;(3) the deformation activation energy and the strain rate sensitivity index were increasing and decreasing,respectively.The deforming mechanism was the comprehensive role between dislocation gliding and climbing behavior at high temperature.