热处理对选区激光熔化Al-Mn-Mg-Sc-Zr合金力学性能和腐蚀行为的影响  

Effect of heat treatment on mechanical property and corrosion behaviour of selective laser melted Al-Mn-Mg-Sc-Zr alloys

作　　者：邓英[1,2] 曹俊昌[1] 赖毅 郭一帆 梁美婵 潘清林 徐国富[1,2] DENG Ying;CAO Junchang;LAI Yi;GUO Yifan;LIANG Meichan;PAN Qinglin;XU Guofu(School of Materials Science and Engineering,Central South University,Changsha 410083,China;Key Laboratory of Nonferrous Metal Materials Science and Engineering of Hunan Province,Central South University,Changsha 410083,China;Guangdong Weiye Aluminum Factory Group Co.,Ltd.,Foshan 528000,China)

机构地区：[1]中南大学材料科学与工程学院,长沙410083 [2]中南大学有色金属材料科学与工程湖南省重点实验室,长沙410083 [3]广东伟业铝厂集团有限公司,佛山528000

出　　处：《中国有色金属学报》2024年第4期1240-1251,共12页The Chinese Journal of Nonferrous Metals

基　　金：湖南省自然科学基金资助项目(2023JJ30671);长沙市自然科学基金资助项目(KQ2208264);湖南省青年骨干教师项目(150220001);国家重点研发计划资助项目(2021YFC1910505);广东省重点领域研发计划资助项目(2020B010186002)。

摘　　要：以Al-4.77Mn-1.37Mg-0.67Sc-0.25Zr(质量分数,%)合金粉末为原料,在激光功率330 W和扫描速率700 mm/s下进行选区激光熔化(Selective laser melting,SLM)形成SLM Al-Mn-Mg-Sc-Zr合金,结合慢应变速率拉伸实验、电化学测试、析氢浸泡实验及显微组织表征手段,分析了(350℃,8 h)热处理对SLM Al-Mn-Mg-Sc-Zr合金力学性能和腐蚀行为的影响。结果表明:SLM Al-Mn-Mg-Sc-Zr合金力学性能优异,抗拉强度、屈服强度和伸长率分别为423 MPa、376 MPa和25.1%。热处理后,SLM Al-Mn-Mg-Sc-Zr合金晶内析出大量针棒状纳米Al_(6)Mn相,抗拉强度和屈服强度分别提升至509 MPa和478 MPa。此外,SLM Al-Mn-Mg-Sc-Zr合金具有良好的耐蚀性能,热处理可以促进SLM Al-Mn-Mg-Sc-Zr合金的钝化,在-0.5 V极化电位时出现钝化台阶,降低SLM Al-Mn-Mg-Sc-Zr合金的电流密度,增加SLM Al-Mn-Mg-Sc-Zr合金的阳极极化率,使SLM Al-Mn-Mg-Sc-Zr合金的平均析氢速率从0.242 mL/(cm^(2)·h)降至0.216 mL/(cm^(2)·h),应力腐蚀敏感因子从3.379%降至0.405%。与此同时,热处理也促进了晶内微米富Si相以及晶界富Mn相和Mg相的析出,增加了SLM Al-Mn-Mg-Sc-Zr合金点蚀形核位置,增大了SLM Al-Mn-Mg-Sc-Zr合金的晶界电化学成分非均匀性,降低了SLM Al-Mn-Mg-Sc-Zr合金的点蚀和晶间腐蚀抗力。The selective laser melted(SLM)alloy was prepared at laser power of 330 W and scanning speed of 700 mm/s using Al-4.77Mn-1.37Mg-0.67Sc-0.25Zr(mass fraction,%)alloy powder as raw material.The effects of heat treatment(350℃,8 h)on mechanical properties and corrosion behavior of SLM Al-Mn-Mg-Sc-Zr alloy were analyzed by slow strain rate tensile test,electrochemical test,hydrogen evolution test and microstructure characterization.The results show that the mechanical properties of SLM Al-Mn-Mg-Sc-Zr alloy are excellent,the tensile strength,yield strength and elongation reach 423 MPa,376 MPa and 25.1%,respectively.After heat treatment,a large number of needle-like or rod-like Al_(6)Mn phases precipitate,and the tensile strength and yield strength further increase to 509 MPa and 478 MPa,respectively.In addition,SLM Al-Mn-Mg-Sc-Zr alloy has good corrosion resistance,heat treatment can promote the passivation of SLM Al-Mn-Mg-Sc-Zr alloy at polarization potential of -0.5 V,decrease the current density of SLM Al-Mn-Mg-Sc-Zr alloy and increase anode polarizability of SLM Al-Mn-Mg-Sc-Zr alloy.Therefore,the average hydrogen evolution rate of SLM Al-Mn-Mg-Sc-Zr alloy decreases from 0.242 mL/(cm^(2)·h)to 0.216 mL/(cm^(2)·h),and the stress corrosion sensitivity factor of SLM Al-Mn-Mg-Sc-Zr alloy decreases from 3.379%to 0.405%.At the same time,the heat treatment can also accelerate the precipitation of micron-scaled Si-rich phase of SLM Al-Mn-Mg-Sc-Zr alloy in grains and Mn and Mg enriched grain boundary phases,which increases the nucleation sites of pitting corrosion nucleation and the non-uniformity of the electrochemistry at the grain boundary,reduces resistance to pitting corrosion and intergranular corrosion.

关 键 词：选区激光熔化 热处理 应力腐蚀 晶间腐蚀 电化学 显微组织 

分 类 号：TG146.2[一般工业技术—材料科学与工程]