铸态及激光粉末床熔融AlCoCrFeNi_(2.1)共晶高熵合金的微观组织及力学性能  

Microstructure and Mechanical Properties of As-Cast and Laser Powder Bed Fused AlCoCrFeNi_(2.1)Eutectic High-Entropy Alloy

作　　者：唐旭 张昊[1] 薛鹏[1] 吴利辉[1] 刘峰超[1] 朱正旺[1] 倪丁瑞[1] 肖伯律[1] 马宗义[1] TANG Xu;ZHANG Hao;XUE Peng;WU Lihui;LIU Fengchao;ZHU Zhengwang;NI Dingrui;XIAO Bolv;MA Zongyi(Shi-changxu Innovation Center for Advanced Materials,Institute of Metal Research,Chinese Academy of Sciences,Shenyang 110016,China;School of Materials Science and Engineering,University of Science and Technology of China,Shenyang 110016,China)

机构地区：[1]中国科学院金属研究所师昌绪创新中心,沈阳110016 [2]中国科学技术大学材料科学与工程学院,沈阳110016

出　　处：《金属学报》2024年第11期1461-1470,共10页Acta Metallurgica Sinica

基　　金：国家自然科学基金项目No.U21A2043;中国科学院青年创新促进会项目No.2022191;Bintech-IMR研发计划项目No.GYY-JSBU-2022-010。

摘　　要：共晶高熵合金作为一种原位复合材料,因其具有典型的双相层片状组织和良好的流动性能,在组织以及性能调控方面具有巨大的潜力。本工作分别采用真空感应熔炼和激光粉末床熔融(LPBF)制备了AlCoCrFeNi_(2.1)共晶高熵合金,分析了制备工艺对该合金微观组织的影响,并探究了2种样品在室温、500℃和700℃条件下的拉伸性能。结果表明,铸态和LPBF成形样品均呈现出由fcc相和bcc/B2相交替组成的共晶结构。LPBF过程中极高的加热和冷却速率有利于超细均匀共晶层片的形成,并且显著降低了元素偏析。在室温拉伸变形过程中,由于较强的相界强化和双相协同变形特性,使得LPBF成形样品的抗拉强度相较于铸态样品提升了约28%,并获得了10%的良好延伸率。在500℃拉伸条件下,铸态及LPBF成形样品的力学性能均有所下降,这可能归因于合金中剧烈的相变。随拉伸温度升至700℃,铸态样品的力学性能持续降低,而LPBF成形样品表现出更低的抗拉强度和优异的伸长率,其原因是其超细共晶层片在高温条件下易于沿相界发生相对滑动,此时合金的断裂机制以韧性断裂为主。Eutectic high-entropy alloys(EHEAs),as a typical kind of in situ composite,have become a potential alternative for conventional alloys because of their advantages in high-entropy alloys and eutectic alloys.Casting is the conventional preparation method of EHEAs,which is a well-established process with low production efficiency.Laser powder bed fusion(LPBF)is an economical and effective preparation technology that provides a novel way to directly form fine and complex EHEA components.In this study,considering the different application requirements and technical characteristics,AlCoCrFeNi_(2.1)EHEA was prepared by vacuum induction melting and LPBF,respectively.The effect of the preparation process on the microstructure of the alloy was investigated.In addition,tensile properties of the samples at 20,500,and 700°C were investigated.Results showed that as-cast and LPBF-formed AlCoCrFeNi_(2.1)exhibited a eutectic structure composed of alternating fcc and bcc/B2 phases.The high heating and cooling rates during the LPBF process were conducive to the formation of ultrafine and uniform eutectic lamellae,which significantly reduced element segregation.During tensile deformation at room temperature,considering the strong phase boundary strengthening and dual-phase synergistic deformation,the ultimate tensile strength of the LPBF-formed sample was enhanced by about 28%compared with that of the as-cast sample,and a satisfactory elongation of 10%was obtained.At 500°C,the mechanical properties of the ascast and LPBF-formed samples decreased probably because of the severe phase transformation in the alloy.When the testing temperature was increased to 700°C,the mechanical properties of the as-cast sample continued to decrease.The LPBF-formed samples showed a low tensile strength and superior elongation that should be attributed to the eutectic lamellae sliding along the phase boundaries at high temperatures.Meanwhile,the fracture mechanism of the LPBF-formed sample was dominated by ductile fracture.This work could provide a th

关 键 词：共晶高熵合金 激光粉末床熔融 显微组织 力学性能 断裂机制 

分 类 号：TG132.32[一般工业技术—材料科学与工程]