瞬态热变形对2195铝锂合金组织和性能的影响

Effect of transient hot deformation on microstructure and properties of 2195 Al-Li alloy

为探究瞬态热变形对2195铝锂合金组织和性能的影响,基于快速升温-大变形的方法,利用透射电镜和维氏硬度计等测试手段,对比分析了3种不同方案下2195铝锂合金的微观组织和力学性能,3种方案分别为加热保温未变形-时效处理(稳态未变形)、加热保温大变形-时效处理(稳态热变形)和加热不保温大变形-时效处理(瞬态热变形)。研究结果表明,瞬态热变形促进了时效过程中T1相(Al_(2)CuLi)和δ′相(Al_(3)Li)的析出,有利于提高2195铝锂合金的力学性能;另外,瞬态热变形过程中发生了不连续动态再结晶,其晶界处细小的析出相阻碍了晶界迁移,使得瞬态热变形试样晶粒细化显著。在相同热处理制度下,各试样的硬度大小排序为:瞬态热变形试样>稳态热变形试样>稳态未变形试样。

To explore the effect of transient hot deformation on the microstructure and properties of 2195 Al-Li alloy,based on the method of quick heating up-large deformation,the microstructure and mechanical properties of 2195 Al-Li alloy were compared and analyzed under three different schemes.Three kinds of schemes are heating and holding without deformation-aging treatment(steady without deformation),heating and holding with large deformation-aging treatment(steady hot deformation)and heating and no holding with large deformation-aging treatment(transient hot deformation).The research results show that the transient hot deformation promotes the precipitation of T1 phases(Al_(2)CuLi)andδ′phases(Al_(3)Li)during aging,which is beneficial for the improvement of the mechanical properties of 2195 Al-Li alloy.In addition,discontinuous dynamic recrystallization(DDRX)occurs during transient hot deformation.The fine precipitated phases at the grain boundaries hinder the migration of grain boundary,resulting in the significant grain refinement in the transient hot deformation specimen.The order of hardness under the same heat treatment regime is:transient hot deformation specimen>steady hot deformation specimen>steady without deformation specimen.