新型Al-5Ti-0.8C中间合金对Al-Cu-Mn合金组织形貌和高温力学性能的影响

Effect of Al-5Ti-0.8C Master Alloy on Microstructure and Elevated Temperature Mechanical Properties of Al-Cu-Mn Alloy

摘要:

采用自蔓延燃烧反应法制备了一种新型Al-5Ti-0.8C中间合金，在此基础上采用不同含量（0%，0.1%，0.3%，0.5%，质量分数，下同）的中间合金对Al-Cu-Mn合金进行变质处理，研究该中间合金及其含量对Al-Cu-Mn合金组织形貌和高温力学性能的影响。结果表明：新型Al-5Ti-0.8C中间合金能够显著细化Al-Cu-Mn合金的晶粒尺寸，提高合金热处理过程中θ′(Al₂Cu)相的析出密度，且细化析出相尺寸。其次，变质处理后合金的高温抗拉伸强度显著提高，且随着温度升高，抗拉伸强度的下降程度减小，主要原因在于变质处理后合金中析出均匀分布的细小θ′(Al₂Cu)相以及热稳定性高的Al₃(Ti, Zr)纳米颗粒。此外，当Al-5Ti-0.8C中间合金含量为0.3%时，Al-Cu-Mn合金的组织形貌和高温力学性能最优。

Abstract:

A new kind of Al-5Ti-0.8C master alloy was fabricated using a self-propagating combustion reaction method and dilution treatment, and the effects of different Al-5Ti-0.8C master alloy contents (0wt%, 0.1wt%, 0.3wt%, 0.5wt%) on the microstructure and elevated temperature mechanical properties of Al-Cu-Mn alloy were investigated. The results show that the Al-5Ti-0.8C master alloy refines the Al-Cu-Mn alloy, increases the amount of θ′(Al₂Cu) precipitates, and reduces their size during heat treatment, resulting in the grain refinement. Moreover, this new master alloy obviously improves the elevated temperature mechanical properties of Al-Cu-Mn alloy, mainly due to the precipitation strengthening caused by the uniform distribution of second phases and fine θ′(Al₂Cu) precipitates, and the formation of Al₃(Ti, Zr) nanoparticles with high thermal stability. Furthermore, the microstructure and mechanical properties of Al-Cu-Mn alloy with 0.3wt% Al-5Ti-0.8C master alloy show the optimal status.