摘要
采用电弧熔炼法制备了4个铸态为FCC+B2共晶组织和B2单相的Al-Co-Cr-Fe-Ni高熵合金,分析了其相变点,并研究了600,800,1000℃下真空退火10 d对这些合金显微组织及硬度的影响。研究表明:AlCoCrFeNi_(2.1)和Al_(0.75)Co_(1.25)CrFeNi合金的共晶反应温度分别为1344℃和1359℃。600~1000℃退火10 d对AlCoCrFeNi_(2.1)高熵合金的显微组织无明显影响;而随着退火温度的增加,Al_(0.75)Co_(1.25)CrFeNi合金中共晶组织的两相层片间距增加。随着Al含量的增加,Al_(x)Co_(2-x)CrFeNi合金的B2相稳定性增加,合金的固相线温度明显升高,显微硬度也明显增加。铸态为B2单相的AlCoCrFeNi合金加热到605.7℃以上会转变为组织细小的FCC+B2+σ三相;继续加热到906.8℃以上,σ相消失,FCC相呈大块状分布。而Al_(1.75)Co_(0.25)CrFeNi合金需要加热到982.4℃以上才会分解为两种不同成分的B2相。实验发现:退火温度越高,合金的显微硬度越低,这些合金在800℃以下都具有较高的硬度。
Four Al-Co-Cr-Fe-Ni high entropy alloys,which have FCC+B2 eutectic structure or B2 single phase in as-cast state,were melted by arc melting.The phase transformation point was firstly examined.The effect of annealing temperature at 600℃,800℃and 1000℃for 10 days on microstructure and hardness of these alloys were studied.The experimental results showed that the FCC+B2 eutectic reaction temperatures for the AlCoCrFeNi_(2.1)and Al_(0.75)Co_(1.25)CrFeNi alloys are 1344℃and 1359℃,respectively.Annealing at 600-1000℃for 10 days had no obvious effect on the microstructure of AlCoCrFeNi_(2.1)high entropy alloy,but with the increase of annealing temperature,the lamellar spacing between FCC and B2 phases in eutectic structure of Al_(0.75)Co_(1.25)CrFeNi alloy increased.With the increase of Al content,the phase stability of B2 phase in the Al_(x)Co_(2-x)CrFeNi alloys increased,and the solidus temperature and microhardness of these alloy increased obviously.When the as-cast AlCoCrFeNi alloy was heated above 605.7℃,it would turn into FCC+B2+σthree-phase,but the microstructure was very fine.When heated up to above 906.8℃,theσphase disappeared,and FCC phase was massive.However,Al_(1.75)Co_(0.25)CrFeNi alloy needed to be heated above 982.4℃to decompose into two different B2 phases.It was found that the higher the annealing temperature,the lower the microhardness of the alloy.All these alloys have high hardness below 800℃.
作者
吴长军
熊伟
周琛
刘亚
苏旭平
WU Changjun;XIONG Wei;ZHOU Chen;LIU Ya;SU Xuping(Jiangsu Key Laboratory of Materials Surface Science and Technology,Changzhou University,Changzhou 213164,China;School of Materials Science and Engineering,Changzhou University,Changzhou 213164,China)
出处
《常州大学学报（自然科学版）》
CAS
2021年第3期1-8,共8页
Journal of Changzhou University：Natural Science Edition
基金
国家自然科学基金资助项目(51771035)
江苏省自然科学基金资助项目(BK20161190)。
