不同Cd含量对Al-Cu合金组织与性能的影响

Effects of Cd Variations on Microstructures and Mechanical Properties of Al-Cu Alloys

通过室温拉伸、SEM、EDS和TEM分别对试样进行性能测试及微观表征,研究了不同Cd含量对Al-Cu合金微观组织和力学性能的影响.研究表明:在175℃人工时效过程中,不同Cd含量的合金具有相似的时效响应规律,Cd元素能促进合金强化相θ′的析出,与含质量分数为0.10%Cd的合金相比,含质量分数为0.19%Cd与0.36%Cd的合金达到峰时效的时间缩短且峰值硬度值提升.在峰时效状态下,当Cd元素质量分数从0.10%增加到0.19%时,合金屈服强度从384.2 MPa提升到422.8 MPa,延伸率从8.5%降到7.1%;Cd元素质量分数为0.36%时强度几乎不再变化,延伸率则继续下降至5.86%.TEM结果显示含质量分数为0.19%Cd的合金中析出相数量多且尺寸小,对合金析出强化效果更明显;当Cd质量分数为0.36%时,合金中析出相长度稍微变短,数量增多不明显.与此同时,含质量分数分别为0.19%和0.36%Cd的合金断口表面存在富Cd晶间残留相,这对Al-Cu合金性能的提升是有害的.

The effects of different Cd contents on the microstructure and mechanical properties of Al-Cu alloy were studied through mechanical properties testing as well as SEM,EDX and TEM.The results show that the alloys with different Cd content have the similar aging response law in artificial aging process at 175℃.Cd element can promote the precipitation of strengthening phaseθ’of Al-Cu alloys.The time for peak aging of 0.19%Cd alloy and0.36%Cd alloy was shortened and the peak hardness value was obtained upgrade.In the peak aging state,when the Cd element mass-fraction increased from 0.10%to 0.19%,the alloy yield strength increased from 384.2 MPa to422.8 MPa,and the elongation decreased from 8.5%to 7.1%,but the yield strength did not change and the elongation decreased to 5.86%when the mass-fraction of Cd was 0.36%.TEM shows that the number of precipitated phases in the 0.19%Cd alloy was large and the size was small,so that the precipitation strengthening effect of the alloy was more obvious;the length of precipitated phases in the 0.36 wt.%Cd alloy became slightly shorter,and the increase of the number was not obvious.At the same time,there was Cd-rich intercrystalline residual phase on the fracture surface of the alloy containing 0.19 wt.%and 0.36 wt.%Cd,which was harmful for improving the properties of Al-Cu alloy.