Ni-Co-Al合金非连续沉淀相变及其对合金力学性能的强韧化作用研究

多元合金中非连续沉淀(Discontinuous Precipitation,DP)的出现通常被认为对力学性能有害。最近研究表明,Ni-Co-Al合金通过非连续沉淀析出过程可以形成双相层状纳米结构,实现“类珠光体型”的强化效果。为了进一步探究非连续沉淀对Ni-Co-Al合金力学性能的影响,总结并讨论了在不同合金成分和热处理条件下,Ni-Co-Al合金的显微组织及力学性能的变化规律。结果表明,Co元素含量的增加以及时效温度的降低有利于非连续沉淀析出,而且接近完全转变的DP组织能有效地提高Ni-Co-Al合金的强度和塑性。通过理论模拟、显微结构表征和力学性能分析,讨论了非连续沉淀的析出行为以及该反应对Ni-Co-Al合金力学性能的强韧化作用机制,指出该处理方法为镍基高温合金的强韧化研究提供了新的思路。

Investigations of Discontinuous Precipitation and Effects of Strengthening-Toughening Studies on Ni-Co-Al Alloys

The occurrence of discontinuous precipitation(DP)in multi-component alloys is usually considered to be deleterious to the mechanical properties.However recent studies have shown that lamellar nanostructure can be produced in Ni-Co-Al alloys via DP,which can be used to strengthen alloys similar to pearlites in steel.In order to further investigate the effect of discontinuous precipitation on the mechanical properties of Ni-Co-Al alloy,this article summarizes and discusses the changes in the microstructure and mechanical properties of the alloy under different alloy compositions and heat treatment conditions.The results show that the increase of Co content and lower aging temperature are favorable for the occurrence of discontinuous precipitation,and near-complete DP structure can effectively improve the strength and plasticity of Ni-Co-Al alloys.Through theoretical modeling,microstructure characterization and mechanical property analysis,the precipitation behavior of discontinuous precipitation and the mechanism of the reaction to strengthen and toughen Ni-Co-Al alloy are also discussed.This treatment method provides new ideas for researches on the strengthening and toughening of Ni-based superalloys.