摘要
通过电弧熔炼法制备了一系列fcc型Co_(x)CrFeMnNi_(2-x)(x=0.25~1.5)高熵合金,并于600~1000℃真空退火120~360 h,进而研究了Co和Ni含量、退火温度及时间对合金显微组织和耐蚀性的影响。结果表明,这些铸态合金均由fcc单相组成。600~1000℃退火后,除x=1.5的合金中会形成少量的hcp相外,其他合金没有相变。铸态Co_(x)CrFeMnNi_(2-x)合金主要由粗大的树枝晶组成,合金的耐蚀性随Co含量的增加而逐渐降低。600~1000℃退火会明显改变合金的金相显微组织。600℃退火后,由于晶界迁移截断枝晶主干,合金组织得到了细化;同时,由于粗大的晶界增多,合金耐蚀性明显降低。800℃退火120 h后,合金中形成了曲折的等轴晶界,但晶内仍有明显的网状编织的亚晶;此时,合金的耐蚀性得到大幅提升。进一步延长退火时间或升高退火温度可使晶界变得平滑细小,晶内的编织网状亚晶逐渐消失,合金的耐蚀性也将进一步提升。这些结果将为fcc型高熵合金的成分设计及组织调控提供依据。
A series of fcc-type Co_(x)CrFeMnNi_(2-x)(x=0.25—1.5)high-entropy alloys were prepared by arc melting method and were vacuum annealed at 600—1000℃for 120—360 h in this work.The influence of Co and Ni contents,annealing temperature and annealing time on microstructure and corrosion resistance of these alloys were investigated.The results show that all the investigated as-cast alloys are composed of single fcc phase.Except for Co_(1.5)CrFeMnNi_(0.5) alloy,in which a small amount of hcp phase is formed,there is no phase transformation or precipitation in other alloys after 600—1000℃annealing.The as-cast Co_(x)CrFeMnNi_(2-x) alloys are mainly composed of coarse dendrites.Their corrosion resis-tance gradually decreases with the increase of Co content.Experimental results indicate that the metallographic microstructure of the Co_(x)CrFeMnNi_(2-x) alloys significantly change after annealing.The dendritic structure of these alloys becomes much finer after 600℃annealing,because the trunks of the dendrites are truncated by grain boundary migration.The corrosion resistance of the alloys are significantly reduced due to the increase of coarse grain boundary.After annealing at 800℃for 120 h,tortuous equiaxed grain boundaries are formed with corrosion resistance greatly improved,while the woven net-like subcrystals still exist in the equiaxed grains.Moreover,further prolonging annealing time or increasing annealing temperature can smoothen and refine the grain boundaries.The woven network sub-crystals in the crystal gradually disappear,and the corrosion resistance of the alloys is further improved.These results will provide a basis for designing and microstructure controlling of the fcc-type high-entropy alloys.
作者
王权
吴长军
徐雪薇
彭浩平
刘亚
苏旭平
WANG Quan;WU Changjun;XU Xuewei;PENG Haoping;LIU Ya;SU Xuping(Jiangsu Key Laboratory of Material Surface Science and Technology,School of Materials Science and Engineering,Changzhou University,Changzhou 213164,Jiangsu,China;Jiangsu Collaborative Innovation Center for Photovoltaic Science and Engineering,Changzhou University,Changzhou 213164,Jiangsu,China)
出处
《材料导报》
EI
CAS
CSCD
北大核心
2022年第11期139-145,共7页
Materials Reports
基金
国家自然科学基金(51771035,51971039)。
关键词
退火处理
高熵合金
显微组织
枝晶
耐蚀性
annealing treatment
high entropy alloy
microstructure
dendrite
corrosion resistance
