固溶温度对Al-11.7Zn-2.2Mg-2.0Cu-0.12Zr铝合金组织及性能的影响

Effect of solution temperature on the properties and microstructure of a Al-11.7Zn-2.2Mg-2.0Cu-0.12Zr aluminum alloy

摘要:

采用拉伸试验机、金相显微镜、XRD、SEM以及EMPA等手段对合金总含量超过15 wt.%的新型超高强铝合金不同固溶温度处理后的组织与性能变化规律进行了研究。结果表明：晶内的固溶度随温度升高逐渐增加，在474℃时基本达到稳定状态，此时，约有99 wt.%的Zn、Mg以及75 wt.%的Cu溶入晶内，其余的合金元素富集在晶界第二相内，此时第二相主要由含Cu的T相构成；合金最佳固溶温度为474℃，此时合金的抗拉强度为688 MPa、延伸率为8 %；温度为476℃时，合金局部区域出现轻微过烧，导致延伸率迅速降低；断口分析显示，随固溶温度的提高，再结晶程度增加，晶界第二相数量减少，合金的拉伸断口由较低温度时的沿晶+穿晶混合断口转变为较高温度时的沿晶断口为主。

Abstract:

Effect of solution temperature on solid solubility, tensile properties, microstructure and fractography of a new Al-Zn-Mg-Cu-Zr aluminum alloy were studied by tensile testing, optical microscopy, XRD, SEM and EPMA. The results indicated that the solid solubility of matrix increase with the increasing temperature, and when it reach stable state at 474℃, about 99 wt.%Zn, Mg and 75 wt.%Cu enter matrix, the residual elements enrichment in the second phase particles（T phase）located on grain boundary. The optimal solution temperature is 474℃, the tensile strength of forge can get up to 688MPa, and elongation is 8%. At 476℃, the slight over-burned in local region is observed, which lead to the decrease of elongation rapidly. It is found that the tensile fractography was affected by the volume fraction of residual particles and the recrystallization level of deformed grains. With the temperature increasing, the fractography transform from intergranular cracking mixed dimple-type transgranular cracking to intergranular cracking.