CrNbTiVAl_(x)难熔高熵合金的组织、力学性能和高温氧化行为  

Microstructure,Mechanical Properties,and High-Temperature Oxidation Behaviors of the CrNbTiVAl_(x) Refractory High-Entropy Alloys

作　　者：朱满[1] 张成 许军锋[1] 坚增运[1] 惠增哲[1] ZHU Man;ZHANG Cheng;XU Junfeng;JIAN Zengyun;XI Zengzhe(School of Materials Science and Chemical Engineering,Xi'an Technological University,Xi'an 710021,China)

机构地区：[1]西安工业大学材料与化工学院,西安710021

出　　处：《金属学报》2025年第1期88-98,共11页Acta Metallurgica Sinica

基　　金：国家自然科学基金项目Nos.51971166和51904218。

摘　　要：难熔高熵合金(RHEAs)具有高热稳定性、良好的高温力学性能和优异的高温抗氧化性能,有望作为一种潜在的耐高温结构材料使用。为了降低RHEAs密度、改善其高温抗氧化性能,本工作向CrNbTiV合金中添加Al元素,制备了一系列CrNbTiVAl_(x)(x=0.25、0.5、0.75、1.0)难熔高熵合金。采用XRD、SEM、EDS和电子万能试验机等手段研究Al含量对CrNbTiV难熔高熵合金微观组织、力学性能和高温氧化行为的影响规律。结果表明,CrNbTiVAl_(x)合金的微观组织由bcc、Laves和α-Ti相组成,bcc相以等轴晶形式分布。随着Al含量的增加,合金的密度逐渐减小,屈服强度由2037 MPa降低至1371 MPa;比屈服强度由CrNbTiVAl_(0.75)合金的215.93 MPa·cm^(3)/g增加至CrNbTiVAl_(0.25)合金的323.33 MPa·cm^(3)/g。CrNbTiVAl_(x)合金在900℃氧化时的氧化动力学遵循抛物线规律,增加Al含量有利于提高合金的高温抗氧化性能。CrNbTiVAl_(x)合金氧化后的氧化产物是由Al_(2)O_(3)、(CrNbTiVAl)O_(2)和VO_(x)组成的混合结构。当Al含量较低时,合金表面形成的连续、紧密的复杂氧化物(CrNbTiVAl)O_(2)有效阻止了O_(2)向基体内的扩散。随着Al含量的增加,复杂氧化物(CrNbTiVAl)O_(2)含量减少,表面形成了更加致密、连续且细小的Al_(2)O_(3)氧化膜,从而显著提高了合金的高温抗氧化性能。Owing to their high thermal stability,good high-temperature mechanical properties,and excellent high-temperature oxidation resistance,refractory high-entropy alloys(RHEAs)are strong candidates for structural materials in high-temperature applications.To reduce the density and improve the high-temperature oxidation resistance of RHEAs,in this study,the Al element was added into CrNbTiV alloys,forming a series of CrNbTiVAl_(x) RHEAs(x=0.25,0.5,0.75,1.0).The effects of Al content on the microstructure,mechanical properties,and high-temperature oxidation behaviors of the CrNbTiV RHEAs were studied using XRD,SEM,EDS,and an electronic universal testing machine.A mixture of bcc,Laves,and α-Ti phases was found in the CrNbTiVAl_(x) RHEAs and equiaxed grains were observed in the bcc phase.Increasing the Al content decreased the density of the alloys and reduced the yield strength from 2037 to 1371 MPa.The specific yield strength ranged from 215.93 MPa·cm^(3)/g in CrNbTiVAl_(0.75) to 323.33 MPa·cm^(3)/g in CrNbTiVAl_(0.25).After oxidation at 900 ℃,the CrNbTiVAl_(x) RHEAs exhibited parabolic oxidation kinetics and their high-temperature oxidation resistance was improved due to increased Al content.The oxidized products were determined as Al_(2)O_(3),(CrNbTiVAl)O_(2),and VO_(x).The surfaces of the alloys with low Al content formed a continuous and compact complex oxide(CrNbTiVAl)O_(2) that effectively prevented the diffusion of O_(2) into the substrate.Increasing the Al content decreased the amount of complex oxide(CrNbTiVAl)O_(2),forming denser,continuous,and finer Al_(2)O_(3) oxides on the surface that appreciably improved the high-temperature oxidation resistance.

关 键 词：难熔高熵合金 组织 力学性能 高温抗氧化性能 

分 类 号：TG113[金属学及工艺—物理冶金]