摘要
难熔高熵合金(Refractory High-Entropy Alloys,RHEAs)因在超高温环境下仍能展现优异的力学性能,被视为极具潜力的新一代高温结构材料,但其固有抗氧化能力不足的特点限制了其实际应用。增材制造(Additive Manufacturing,AM)技术作为一种新兴的材料加工技术,能够实现复杂构件的成形,并通过独特的凝固特征影响材料的高温氧化行为,因此成为当前研究热点。本文综述了近年来增材制造难熔高熵合金(Additive Manufacturing-Refractory High-Entropy Alloys,AM-RHEAs)的氧化研究进展。首先简要介绍了合金设计、典型增材制造工艺及金属氧化的基本理论。随后系统总结了增材制造对氧化行为的双重作用:一方面,快速冷却生成的细晶与多级次组织有助于保护性元素的快速扩散和致密氧化膜的形成;另一方面,孔隙、裂纹与残余应力等缺陷则加速了氧渗透并诱发了膜层剥落。不同合金体系的对比结果表明,含Al合金能形成稳定的α-Al_(2)O_(3)膜,含Cr或Si合金则通过生成Cr_(2)O_(3)、SiO_(2)或复杂氧化物实现协同防护。此外,系统归纳了提升AM-RHEAs抗氧化性能的策略,涵盖了热等静压、退火等后处理技术,以及铝化、硅化和高熵硅化物涂层等表面工程方法。然而当前仍存在长期服役机理不清、工艺参数与性能关联不足等问题。未来需进一步结合多尺度计算模拟与原位表征技术,深化对复杂环境下氧化行为的理解,以推动AM-RHEAs在极端环境下的工程化应用。
Refractory high-entropy alloys(RHEAs)are regarded as promising next-generation structural materials for ultrahigh-temperature applications due to their excellent mechanical properties at high temperatures.However,their practical deployment is hindered by their intrinsic susceptibility to oxidation.Additive manufacturing(AM),as an emerging fabrication technology,enables near-net-shape production of complex components and introduces unique solidification features that significantly affect the high-temperature oxidation behavior,thus becoming a major research focus.This review summarizes recent progress on the oxidation of additive manufacturing-refractory high-entropy alloys(AM-RHEAs).It begins by briefly outlining the principles of alloy design,representative AM processes,and the fundamental theories of metal oxidation.The coupled effects of AM on oxidation are then discussed:rapid solidification produces fine and hierarchical microstructures that promote the diffusion of protective elements and the formation of dense oxide scales,while processing-induced defects such as pores,cracks,and residual stresses accelerate oxygen ingress and trigger scale spallation.A comparison of different alloy systems indicates that Al-containing alloys can form a stableα-Al_(2)O_(3) scale,whereas alloys containing Cr or Si achieve synergistic protection through the formation of Cr_(2)O_(3),SiO_(2),or complex oxides.Furthermore,this paper systematically reviews strategies for enhancing the oxidation resistance of AM-RHEAs,including post-processing techniques like hot isostatic pressing and annealing,as well as surface engineering methods such as aluminizing,siliconizing,and high-entropy silicide coatings.However,current challenges remain,such as an unclear understanding of long-term service mechanisms and an inadequate correlation between process parameters and performance.Future work should further integrate multi-scale computational simulations with in-situ characterization techniques to deepen the understanding of the oxidation behavior in complex environments,thereby promoting the engineering application of AM-RHEAs in extreme environments.
作者
祁宏强
严明
QI Hongqiang;YAN Ming(Department of Materials Science and Engineering,Southern University of Science and Technology,Guangdong Shenzhen 518052,China)
出处
《精密成形工程》
北大核心
2025年第12期15-24,共10页
Journal of Netshape Forming Engineering
基金
国家自然科学基金面上项目(52271032)。
关键词
难熔高熵合金
增材制造
高温氧化
热障涂层
微观结构
refractory high-entropy alloys
additive manufacturing
high-temperature oxidation
thermal barrier coatings
microstructure
