粉末热挤压7075铝合金的显微组织与力学性能  

Microstructure and mechanical properties of powder hot extruded 7075 aluminium alloy

作　　者：井萃汝 张建涛 温利平[1] 肖志瑜[1] JING Cuiru;ZHANG Jiantao;WEN Liping;XIAO Zhiyu(National Engineering Research Center of Near-Net-Shape Forming for Metallic Materials,South China University of Technology,Guangzhou 510640,China)

机构地区：[1]华南理工大学国家金属材料近净成形工程技术研究中心,广州510640

出　　处：《粉末冶金材料科学与工程》2022年第2期140-150,共11页Materials Science and Engineering of Powder Metallurgy

基　　金：广东省重大科技攻关项目(2019B010942001);国家自然科学基金资助项目(51627805)。

摘　　要：采用粉末热挤压法制备7075铝合金棒材,利用扫描电镜(SEM)、透射电镜(TEM)和X射线衍射仪(XRD)分析材料的显微组织,测定材料的拉伸性能,研究挤压比对7075铝合金棒材组织与力学性能的影响,并对强化机制进行理论计算。结果表明:在500℃、挤压比分别为9、16、25、36条件下进行热挤压,挤压过程中有大量第二相MgZn_(2)脱溶析出。随挤压比增大,粉末颗粒间的冶金结合更加充分,合金的抗拉强度与伸长率提高,挤压比为36的合金抗拉强度达到492 MPa,伸长率为27.6%,断裂方式为韧−脆性混合断裂,强化机制为细晶强化、位错强化、第二相强化与固溶强化共同作用。7075 aluminum alloy bar was prepared by powder hot extrusion method.The microstructures of the alloy bar were examined by scanning electron microscopy(SEM),transmission electron microscopy(TEM),and X-ray diffraction(XRD).In addition,the tensile properties of the samples were also tested.The influences of the extrusion ratio on the microstructure and mechanical properties of the bar were investigated,and the strengthening mechanism was calculated in theory.The results show that a large number of second phase MgZn_(2) precipitates are desolventized and precipitated during hot extrusion at 500℃with extrusion ratios of 9,16,25,and 36.With increasing extrusion ratio,the metallurgical bonding between the powder particles becames more sufficient,and the tensile strength and elongation of the alloy increase continuously.A high tensile strength of 492 MPa with an elongation of 27.6%is obtained at an extrusion ratio of 36.The fracture mode is a ductile-brittle-bonding fracture.The strengthening mechanism is the combined action of fine-grain strengthening,dislocation strengthening,second phase strengthening and solution strengthening.

关 键 词：粉末热挤压 7075铝合金 显微组织 力学性能 强化机制 

分 类 号：TB331[一般工业技术—材料科学与工程]