T6热处理对挤压态Al-Si-xEr合金组织及性能的影响

Effect of T6 Heat Treatment on Microstructure and Properties of Extruded Al-Si-xEr Alloy

摘要: 为改变Al-Si合金的第二相尺寸、数量、分布，改善合金的电学和力学性能，本文选用稀土元素Er作为合金元素，制备了Al-4Si、Al-4Si-0.5Er、Al-4Si-1Er合金。通过光学金相显微镜(OM)、场发射扫描电镜(SEM)、四电极法测电阻、万能拉伸试验机、显微硬度计等方法和设备，探究了稀土Er及T6热处理对挤压态Al-4Si、Al-4Si-0.5Er、Al-4Si-1Er合金的微观组织、相组成、电学和力学性能的影响。结果表明：稀土元素Er有利于Si由固溶态转变成析出态，增加了第二相种类和数量，减小了第二相尺寸，提高了合金的力学性能，且导电率保持稳定，合金的相组成为：α-Al、共晶硅、ErSi₂、Al₃Er；T6热处理后，合金组织中第二相析出更加充分，Al-4Si-1Er合金的综合性能达到最高，导电率由52.92% IACS上升至 54.96% IACS，提高了4%，抗拉强度为103.5 MPa，伸长率为34.5%，硬度为40.5 HV。

Abstract: In order to change the size, quantity and distribution of the second phase of Al-Si alloy and improve the electrical and mechanical properties of the alloy, Al-4Si, Al-4Si-0.5Er and Al-4Si-1Er alloy were prepared by using rare earth element Er as alloying element. The influence of rare earth Er and T6 heat treatment on the microstructure, phase composition, electrical and mechanical properties of extruded Al-4Si, Al-4Si-0.5Er and Al-4Si-1Er alloys was studied by means of optical metallographic microscope (OM), field emission scanning electron microscope (SEM), four-electrode method for measuring resistance, universal tensile testing machine, micro-hardness tester and other methods and equipment. The results show that the rare earth element Er is beneficial to the conversion of Si from the solid solution state to the precipitation state, increasing the type and quantity of the second phase, reducing the size of the second phase, improving the mechanical properties of the alloy, and maintaining the conductivity. The phase composition of the alloy is: α-Al, eutectic silicon, ErSi₂, Al₃Er. After T6 heat treatment, the second phase of the alloy structure precipitates more fully. The overall performance of the Al-4Si-1Er alloy is the highest, the conductivity increases from 52.92% IACS to 54.96% IACS, increased by 4%, tensile strength is 103.5 MPa, elongation is 34.5%, and hardness is 40.5 HV.