水冷铜模对添加Mn和Zr的6061铝合金微观组织及力学性能的影响

Effects of Water-Cooling Cu Mould on Microstructure and Mechanical Properties of 6061 Aluminum Alloy with Mn and Zr Addition

摘要:

研究了水冷铜模铸造对添加Mn和Zr元素的6061铝合金的微观组织及力学性能的影响。利用金相显微镜、扫描电镜和EDS能谱,分析合金的微观组织；结合X射线衍射分析及Vegard定律,估算铸态及均匀化处理后Mg,Si和Mn元素在合金中的固溶度；通过拉伸实验测试含Mn和Zr 的6061铝合金力学性能。结果表明：水冷铜模亚快速凝固铸造降低了溶质元素Mg、Si、Mn在铸态合金中的偏析,减少了合金的均匀化处理时间；Mn和Zr元素的添加,使晶粒细化明显；水冷铜模使铸态析出相由骨骼状和条状的β铁相转变为颗粒状的α铁相,均匀化处理后主要以颗粒状的α-Al₈(MnFe)₂Si和α-Al₈(MnFeCr)₂Si相存在。采用水冷铜模铸造的含Mn和Zr的6061铝合金,其拉伸性能得到明显改善。经均匀化处理后其抗拉强度达到286MPa、屈服强度127MPa,延伸率17.84%。

Abstract:

Effects of sub-rapid solidification by water-cooling Cu mould on microstructure and mechanical properties of 6061 aluminum alloy with Mn and Zr addition were investigated. Microstructure of the alloys was analyzed by optical microscopy, scanning electron microscopy and EDS energy spectrum. Solubilities of Mg, Si and Mn elements in as-cast and homogenized Al alloys were estimated by X-ray diffraction and Vegard’s Law. Tensile tests were conducted to investigate the mechanical properties of 6061 aluminum alloy. Results showed that both the segregation of Mg, Si and Mn elements and homogenization time were decreased by sub-rapid solidification. The grain size had also been refined significantly by adding Mn and Zr elements. As-cast precipitated phase was transformed into α-Fe phase of granulate from β-Fe of bone and strip by water-cooling Cu mould., and they were maily granular α-Al₈(MnFe)₂Si和α-Al₈(MnFeCr)₂Si after homogenization treatment. Tensile properties of Al alloy with Mn and Zr addition casted by water-cooling Cu mould. The UTS, YS and Elongation of homogenized alloy researches to 286Mpa, 27Mpa and 17.84%, respectively.