CAJ | 학술논문

为了探索热处理工艺对AlCoCrFeNiTi0.5高熵合金的显微组织和硬度的影响,采用水冷铜坩埚真空感应悬浮熔炼法制备合金,然后对合金样品进行不同温度、不同冷却方式和不同保温时间的热处理,研究合金的显微组织和硬度的变化规律。结果表明：AlCoCrFeNiTi0.5高熵合金制备态相结构为两种成分不同的BCC相,微观组织由树枝晶、枝晶间和共晶组织(α+β)组成,共晶组织α相上弥散分布着大量纳米粒子。经过热处理后,合金中析出σ相,硬度均大于660.00 HV,其中800℃退火2 h后合金硬度达最大值773.28 HV,高出制备态合金硬度176.22 HV。炉冷比空冷和水冷更能提高合金的硬度。首次发现合金具有晶界硬化现象,晶界硬度均比晶粒硬度大140.00 HV左右。合金试样在800℃下保温480 h后,其组织结构和硬度均无太大变化,具有良好的热稳定性。
위료탐색열처리공예대AlCoCrFeNiTi0.5고적합금적현미조직화경도적영향,채용수랭동감과진공감응현부용련법제비합금,연후대합금양품진행불동온도、불동냉각방식화불동보온시간적열처리,연구합금적현미조직화경도적변화규률。결과표명：AlCoCrFeNiTi0.5고적합금제비태상결구위량충성분불동적BCC상,미관조직유수지정、지정간화공정조직(α+β)조성,공정조직α상상미산분포착대량납미입자。경과열처리후,합금중석출σ상,경도균대우660.00 HV,기중800℃퇴화2 h후합금경도체최대치773.28 HV,고출제비태합금경도176.22 HV。로랭비공랭화수랭경능제고합금적경도。수차발현합금구유정계경화현상,정계경도균비정립경도대140.00 HV좌우。합금시양재800℃하보온480 h후,기조직결구화경도균무태대변화,구유량호적열은정성。
AlCoCrFeNiTi0. 5 high entropy alloy was prepared by cold crucible levitation melting and heat treated in different conditions, including different temperatures, time and cooling methods, to explore the effect of heat treatment on microstructure and hardness. The results show that the as-pre-pared sample is composed of two BCC phases with different compositions and its microstructure con-sists of dendrite, interdendrite and eutectic structure (α+β) ,and there are a lot of nanoparticles dif-fusely distributing on α phase. The hardnesses of all the annealed samples exceed 660. 00HV, due to the precipitation of σ phase. The maximum hardness reaches 773.28 HV when annealed at 800 ℃, 176.22 HV higher than that of the as-prepared alloy. Furnace cooling is more effective to increase the hardness of the alloy than air cooling and quenching cooling. Grain boundary hardening phenomenon was observed for the first time, for which the hardness of grain boundary is about 140.00 HV higher than that of the grains. It was found that the microstructure and hardness of the alloy have no noticeable changes even after annealed at 800 ℃ for 480 h, showing good thermal sta-bility of AlCoCrFeNiTi0. 5 high entropy alloy.