银镁合金内氧化组织及断裂特征  

Internal oxidation structure and fracture characteristics of Ag-Mg alloy

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作  者:周龙海 郑学军 陈昊 赵涛 ZHOU Long-hai;ZHENG Xue-jun;CHEN Hao;ZHAO Tao(Xi'an Noble Rare Metal Materials Co.Ltd.,Xi’an 710201,China;Western Metal Materials Co.Ltd.,Xi’an 710201,China)

机构地区:[1]西安诺博尔稀贵金属材料股份有限公司,西安710201 [2]西部金属材料股份有限公司,西安710201

出  处:《贵金属》2021年第2期9-14,共6页Precious Metals

摘  要:采用真空感应熔炼法制备Ag-0.2Mg合金,用金相显微镜、扫描电镜、维氏硬度仪和电子万能试验机分析合金内氧化的组织及力学性能,研究合金拉伸断裂特征。结果表明,在小于550℃处理后,组织为细小等轴晶粒;大于650℃处理时,表面存在细晶区,内部晶粒逐渐长大,氧化界面向中心移动。内氧化温度升高,硬度逐渐降低,强度增加,延伸率降低。650℃和750℃内氧化后,细晶区断口平滑,内氧化组织为沿晶断裂,未氧化组织为准解理断裂;750℃内氧化后断裂末端区出现微孔聚合型断裂;850℃时断口为小平面状沿晶断裂,不同晶粒及不同晶面的微观断裂特征不一致。同一晶粒两个晶面的微观韧窝中有MgO团簇,形状主要为方形,两个晶面的Mg原子、MgO团簇分布不同。The Ag-0.2Mg alloy was prepared by a vacuum induction melting method.Its microstructure and mechanical properties were characterized by metallographic microscope,scanning electron microscope,Vickers hardness tester and electronic universal testing machine.The tensile fracture characteristics of the alloy were studied.The results showed that the microstructure consisted of fine equiaxed grains after treatment at less than 550℃.When the treatment temperature was higher than 650℃,there was a fine grain zone on the surface.The sizes of inner grains gradually increased and the oxidation interface moved to the center part.Its hardness and elongation decreased with the increase of internal oxidation temperature,while its strength increasesd with internal oxidation temperature.After oxidation at 650℃and 750℃,the fracture of fine grain zone was smooth.The internal oxidation structure was intergranular fracture.The non-oxidized structure was quasi cleavage fracture.After oxidation at 750℃,microporous polymerization fracture occured at the end of fracture.At oxidation temperature of 850℃,the fracture was small plane intergranular fracture,and the micro fracture characteristics of different grains and different crystal planes were not consistent.There were MgO clusters in the micro dimples of two crystal faces of the same grain,which were mainly square in shape.The distribution of Mg atoms and MgO clusters on the two planes was different.

关 键 词:银镁合金 显微组织 维氏硬度 沿晶断裂 准解理断裂 

分 类 号:TG146.32[一般工业技术—材料科学与工程]

 

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