球磨时间对MA-SPS法制备FeCoCrAlNiB高熵合金微观结构、硬度和断裂韧性的影响  

Effect of ball milling time on microstructure, hardness and fracture toughness of FeCoCrAlNiB high-entropy alloy prepared by MA-SPS method

作　　者：李志聪 龙莹[1] 车金涛 林华泰 LI Zhicong;LONG Ying;CHE Jintao;LIN Huatai(School of Electromechanical Engineering,Guangdong University of Technology,Guangzhou 510006,China)

机构地区：[1]广东工业大学机电工程学院,广州510006

出　　处：《材料科学与工艺》2022年第5期82-89,共8页Materials Science and Technology

基　　金：广东省自然科学基金资助项目(2021A1515011820)。

摘　　要：采用机械合金化(MA)和放电等离子烧结(SPS)相结合的方法制备FeCoCrAlNiB高熵合金。研究球磨时间(1、5、10、20、30和40 h)对合金相成分、微观结构、硬度和断裂韧性的影响。结果表明:高能球磨过程中各金属元素的合金化顺序为Al→Co→Ni→Fe→Cr;混合粉末球磨20 h后基本形成了单一的BCC固溶体相,其颗粒尺寸约为20μm。对不同球磨时间的混合粉末进行SPS烧结,获得的FeCoCrAlNiB高熵合金主要由无序BCC+B2(Al-Ni)固溶体相和硼化物相(Fe_(2)B等)组成。随着球磨时间的延长,合金中硼化物相含量先减少后增加并主要以网状形式分布,BCC相含量则与之相反;合金硬度随球磨时间的延长逐渐提高,主要是因为合金元素间固溶程度越来越高,硼化物相逐渐增多;但硼化物形成的网状结构会破坏基体的连续性,导致合金断裂韧性逐渐降低。当球磨时间为20 h时,获得的FeCoCrAlNiB高熵合金的维氏硬度(HV)为(10.9±0.2)GPa,断裂韧性(K_(IC))为(4.4±0.2)MPa·m^(1/2),表现出最优的综合性能。FeCoCrAlNiB high-entropy alloys were fabricated by a combination of mechanical alloying(MA)and spark plasma sintering(SPS).Effects of ball milling time(1,5,10,20,30,and 40 h)on phase composition,microstructure,hardness and fracture toughness of alloy samples were studied.Results show that with the increase in milling time,the alloying sequence of the alloy elements was Al→Co→Ni→Fe→Cr.After ball milling of mixed powders for 20 h,a single BCC solid solution with particle size of about 20μm was formed.The mixed powders were sintered by SPS method with different ball milling time,and the obtained FeCoCrAlNiB high-entropy alloys were mainly composed of disordered BCC+B2(Al-Ni)solid solution phases and boride phases(e.g.,Fe_(2)B).With the continuous of the ball milling process,the content of boride phases in the alloy first decreased gradually and then increased,which was mainly distributed in the form of a network,while the content of BCC phases was opposite.The hardness of FeCoCrAlNiB high-entropy alloy gradually increased with the increase in ball milling time,which was mainly caused by the increase in solid solution degree among alloy elements and the gradual increase in boride phase content.However,the continuity of the boride network structure in the matrix could be destroyed,resulting in the gradual decrease in the alloy fracture toughness.When the ball milling time was 20 h,FeCoCrAlNiB high-entropy alloys with relatively good comprehensive properties(HV=(10.9±0.2)GPa,K_(IC)=(4.4±0.2)MPa·m^(1/2))were obtained.

关 键 词：高熵合金 机械合金化 放电等离子烧结 球磨时间 硼化物 

分 类 号：TB139[理学—物理]