固溶处理对AZ91D镁合金时效态微观组织和性能的影响  

Effect of solid solution treatment on aged microstructure and performance of magnesium alloy AZ91D

作　　者：马颖[1] 齐玉明 韩秋华[1] 王晟[1] 孙乐[1] MA Ying QI Yu-ming HAN Qiu-hua WANG Sheng SUN Le(State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals, Lanzhou Univ. of Tech. , Lanzhou 730050, Chin)

机构地区：[1]兰州理工大学省部共建有色金属先进加工与再利用国家重点实验室,甘肃兰州730050

出　　处：《兰州理工大学学报》2017年第5期1-10,共10页Journal of Lanzhou University of Technology

基　　金：甘肃省创新研究群体计划基金(1111RJDA011)

摘　　要：以AZ91D镁合金为研究对象,研究了固溶处理对后期时效处理效果的影响.结果表明:415℃固溶处理5h后,铸态AZ91D镁合金中分布在晶界处的网状脆性相β-Mg_(17)A_(12)基本全部溶入基体相α-Mg中.后续时效期间沉淀相β-Mg_(17)A_(12)主要在晶界处不连续析出细小条状晶;而在晶内则连续析出颗粒状或短棒状晶.固溶时效处理后析出的β-Mg_(17)A_(12)相尺寸较铸态时大幅减小.晶内析出的β-Mg_(17)A_(12)相尺寸和间距小于400nm时,对提高合金力学性能的贡献很大.拉伸断口上撕裂片越大、解理台阶越多,则晶内析出β-Mg_(17)A_(12)相的尺寸越小、数量越多、分布越弥散,极有利于大幅提高合金的力学性能.415℃固溶处理10、24h后再经200℃时效处理16h,合金的抗拉强度出现2个峰值,较铸态时分别提高22.2%、34%,硬度提高了35.8%、34.7%.The effect of solid solution treatment of magnesium alloy AZ91D on subsequent ageing treatment result was investigated.The result showed that the networked solid brittle β-Mg17A12phase distributed at grain boundaries of as-cast magnesium alloy AZ91D was almost all dissolved into the matrix phaseα-Mg after solid solution treatment at 415℃ for 5 h.The sediment phaseβ-Mg17A12would discontinuously precipitate at grain boundaries in the form of fine strip grain during subsequent ageing while continuously precipitate inside the grains with granular or short rod shape.After aging and solid solution treatments,the size of precipitatedβ-Mg17A12phasewould greatly reduce compared with that of as-cast case.The contribution of AZ91D to its mechanical performance would be great when the size and interval ofβ-Mg17A12phase precipitated inside the grains were less than 400 nm.The bigger the teared slice and the more the cleavage steps on tensile fracture were,the smaller the size,the greater the number,and the more scattered the distribution of the precipitatedβ-Mg17A12 phase inside the grains would be,that would be extremely beneficial to improvement on mechanical properties of AZ91D .Tensile strength would have two peaks after solid solution and aging treatment.The tensile strength of AZ91D would be increased by22.2% after solid solution treatment at 415 ℃ for 10 h followed by aging treatment at 200 ℃ for 16 h when compared with that of as-cast case while would increase by 34% at the same treatment temperature for 24 h.Also,the corresponding hardness would be improved by 35.8% and 34.7%,respectively.

关 键 词：AZ91D镁合金 固溶处理 时效处理 β-Mg17Al12相 力学性能 

分 类 号：TG146[一般工业技术—材料科学与工程]