均匀化处理对挤压态Al-4Si(-0.2Er)合金显微组织及性能的影响

Effect of homogenization process on microstructure and properties of as-extruded Al-4Si(-0. 2Er) alloy

为改变Al-Si合金中第二相的尺寸、形貌及分布,改善合金的电学和力学性能,选用稀土元素Er作为合金化元素,制备了Al-4Si、Al-4Si-0.2Er合金,探究了稀土Er及均匀化处理对挤压态Al-4Si、Al-4Si-0.2Er合金显微组织及电学、力学性能的影响。结果表明:稀土Er有利于促进固溶态Si的析出且形成新相Er Si2,增加了合金中第二相数量,弥散强化效果明显,提高了合金的力学性能,且导电率保持稳定。均匀化处理工艺为540℃×1 h炉冷的Al-4Si-0.2Er合金综合性能较强,均匀化处理促进了第二相的析出,同时减小了第二相尺寸,使其以颗粒状弥散分布,Al-4Si-0.2Er合金的导电率由挤压态的51.61%IACS提高至56.44%IACS,提高了9.4%,炉冷过程导致了合金的力学性能略有下降,抗拉强度为87.80 MPa,伸长率为35.9%,硬度为36.00 HV0.3。

In order to change the size,morphology and distribution of the secondary phase and improve the electrical and mechanical properties of the Ai-Si alloy,Al-4 Si and Al-4 Si-0.2 Er alloys were prepared by selecting rare earth element Er as the alloying element,and the effect of rare earth Er and homogenization on the microstructure,electrical and mechanical properties of the as-extruded Al-4 Si and Al-4 Si-0.2 Er alloys was studied.The results show that rare earth Er is beneficial to promote the precipitation of Si from solid solution and the formation of new phase Er Si2,which increases the number of the secondary phase in the alloy and results in obvious dispersion strengthening effect,so that the mechanical properties of the alloy are improved,with the conductivity keeps stable.When homogenized at 540 ℃ for 1 h then furnace-cooled,the Al-4 Si-0.2 Er alloy has better comprehensive performance,where the homogenization treatment promotes the secondary phase to be precipitated with finer size and dispersed in a granular form.Meanwhile,the conductivity of the Al-4 Si-0.2 Er alloy is increased from 51.61%IACS in the extruded state to 56.44% IACS,which is 9.4% higher.The furnace cooling process results in a slight decrease of mechanical properties of the Al-4 Si-0.2 Er alloy,with tensile strength of 87.80 MPa,elongation of 35.9%,and hardness of 36.00 HV0.3.