摘要
采用电弧熔炼法制备Al_(x)CoCrFeNi(0.5≤x≤0.8)高熵合金,研究1100℃高温热处理对合金微观组织和力学性能的影响。结果表明:铸态合金依次呈现为FCC枝晶组织(x=0.5和0.6)、类共晶组织(x=0.7)和BCC/B2枝晶组织(x=0.8)。相应地,合金屈服强度和抗拉强度分别由291 MPa和733 MPa(x=0.5)提升至1004 MPa和1423 MPa(x=0.7),伸长率由39.7%(x=0.5)降低至6.8%(x=0.7)。经1100℃高温热处理,FCC枝晶相脱溶析出大量棒状B2相,可以提升合金强度,而BCC/B2调幅组织转变为FCC和B2双相组织(FCC相含量增加),可以提升合金塑性。因此,以FCC枝晶组织为主的Al0.5CoCrFeNi合金高温热处理后屈服强度和抗拉强度分别提升至370 MPa和866 MPa,伸长率降低至30.1%。相比而言,Al_(0.6)CoCrFeNi合金调幅组织体积分数有所增加,两种相变对合金组织和性能影响均较大,故而热处理态合金力学性能基本不变。Al_(0.7)CoCrFeNi和Al_(0.8)CoCrFeNi合金调幅组织体积分数更高,热处理态合金均表现为FCC和B2双相组织,合金塑性提升,强度降低。其中热处理态Al_(0.7)CoCrFeNi合金伸长率提升至14.2%,屈服强度和抗拉强度分别降低至586 MPa和1092 MPa。
Al_(x)CoCrFeNi(0.5≤x≤0.8)high-entropy alloys were prepared by arc-melting method and the effect of 1100℃heat treatment on the microstructure and mechanical properties of the alloys was investigated.The results show that the as-cast Al_(x)CoCrFeNi(0.5≤x≤0.8)high-entropy alloys present FCC dendrite(x=0.5 and 0.6),“eutectic-like”structure(x=0.7)and BCC/B2 dendrite(x=0.8)morphologies successively as Al content increases.Correspondingly,the yield strength and tensile strength of the alloys increase from 291 MPa and 733 MPa(x=0.5)to 1004 MPa and 1423 MPa(x=0.7),respectively,and the elongation decreases from 39.7%(x=0.5)to 6.8%(x=0.7).After heat treatment at 1100℃,a large number of rod-like B2 phases are precipitated from the FCC dendrite region,which can improve the strength of heat-treated alloys,while the BCC/B2 spinodal structure transforms into FCC and B2 dual-phase structure,which can enhance the plasticity of heat-treated alloys.Therefore,the yield strength and tensile strength of heat-treated Al_(0.5)CoCrFeNi alloy with FCC dendrite morphology increase to 370 MPa and 866 MPa,respectively,and the elongation decreases to 30.1%.However,both phase transition behaviors have great influence on the microstructure and property of Al_(0.6)CoCrFeNi alloy due to the increasing fraction of spinodal structure.Therefore,the mechanical properties of heat-treated Al_(0.6)CoCrFeNi alloy are basically unchanged in comparison to that of the as-cast alloy.The as-cast Al_(0.7)CoCrFeNi and Al_(0.8)CoCrFeNi alloys contain higher fractions of spinodal structure,while the heat-treated alloys present typical FCC and B2 dual-phase structure,resulting in an increase of plasticity but a decrease of strength.Correspondingly,the elongation of heat-treated Al_(0.7)CoCrFeNi alloy increases to 14.2%,and the yield strength and tensile strength decrease to 586 MPa and 1092 MPa,respectively.
作者
曹雷刚
王帆
侯鹏宇
杨越
崔岩
CAO Leigang;WANG Fan;HOU Pengyu;YANG Yue;CUI Yan(School of Mechanical and Materials Engineering,North China University of Technology,Beijing 100144,China)
出处
《材料工程》
EI
CAS
CSCD
北大核心
2024年第1期249-258,共10页
Journal of Materials Engineering
基金
国家自然科学基金项目(52001006)
北京市教委科技一般项目(KM201910009005)
北京市自然科学基金项目(2194074)
北方工业大学青年毓优人才支持计划(20XN212/001)。
关键词
高熵合金
热处理
相变
微观组织
力学性能
high-entropy alloy
heat treatment
phase transition
microstructure
mechanical property
