Effect Of Alloying Element Content On Microstructure And Mechanical Properties Of Heat Resistant Al-Cu Alloy

Heat-resistant aluminum alloys had been used widely aerospace,mechanical equipment and automotive industry for the excellent specific strength intermediate temperature properties. The development of aerospace and automotive industry put forward higher requirements to the heat resistant aluminum alloy. Materials of high performance, economy and lightweight requirements become more and more urgent.To explore the effects of Ni, Mn and Co contents on microstructure and properties of Al-Cu alloy casting, an orthogonal experiment with three factors and three levels was designed. 9 kinds of heat resistant Al-Cu alloy was prepared according to orthogonal design based on ZL208. The mass fraction of Ni was 1%, 1.5% and 2%, and the mass fraction of Mn was 0.15%, 0.25 and 0.35%, and the mass fraction of Co was 0.15%, 0.25%, 0.35%.The microstructure and mechanical properties of the alloy were obtained by means of optical microscope, scanning electron microscope and Electro-mechanical Universal Testing Machines,The experimental data are analyzed by orthogonal experiment analysis method, research results show that:The level of Ni content had the most significant effect on hardness, tensile strength at room temperature,200℃ and 300℃, and yield strength at 200℃ of aluminum alloys after heat treatment.The effect of Mn content on alloy as cast hardness,and on elongation at room temperature 200℃ and 300℃,yield strength at 200℃ and 300℃ of Al-Cu alloy after heat treatment was the most significant.The content of secondary phase increased with the increase of Ni、Mn、Co content.Ni are enriched in the grain boundary and dendrite space.Effect of Ni content on Second phase content of alloy was the most significant.Effect of Co content on the mechanical properties of heat resistant Al-Cu alloy is not significant.With Ni content level from 1% to 2%, as casting state hardness of heat-resistant Al-Cu alloy increased gradually. On the contrary, the hardness after T7 heat treatment is decreased.According to the results of orthogonal experiment,When The optimized composition of heat resistant Al-Cu alloy are:Al-5.0Cu-1.5Ni-0.35Mn-0.35Co-0.25Sb-0.22Ti-0.22 Zr,Al-5.0Cu-1.5Ni-0.15Mn-0.35Co-0.25Sb-0.22Ti-0.22 Zr,Al-5.0Cu-1.5Ni-0.35Mn-0.25Co-0.25Sb-0.22Ti-0.22 Zr, the tensile strength of heat resistant aluminum alloy has a maximum value at room temperature 200℃ and 300℃.