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机械球磨对CoCrFeMnNi放电等离子烧结高熵合金显微组织和拉伸性能的影响

Effects of mechanical milling on microstructure and tensile properties of CoCrFeMnNi high-entropy alloys produced by spark plasma sintering

  • 摘要: 采用CoCrFeMnNi预合金粉末和放电等离子烧结工艺制备了全致密的粉末高熵合金,研究了球磨预处理工艺对粉末高熵合金显微组织和拉伸性能的影响。结果表明,预合金粉末的球形度随球磨时间的延长不断降低;烧结态高熵合金的物相组成不随球磨参数改变,始终为单一面心立方结构;球磨时间的延长和球料比的增加都会降低高熵合金的晶粒尺寸。随着球磨能量的升高,合金屈服强度不断增大,球料比为7.5:1.0、球磨时长为100 h时,合金屈服强度达到最高,提升约19%,强化贡献主要源于细晶强化;合金抗拉强度先增大后减小,球料比为7.5:1.0、球磨时长为30 h时,合金抗拉强度提升最大,提升约为12%。

     

    Abstract: CoCrFeMnNi high-entropy alloys with nearly full density were fabricated by spark plasma sintering (SPS) process. The effects of mechanical milling on the microstructure and tensile properties of the CoCrFeMnNi alloys were investigated. The results show that the sphericity of the pre-alloyed powders decreases with the milling time increasing. The phase composition of as-SPSed alloys presents a single face-centered cubic structure, and the grain size decreases with the increase of ball-to-powder weight ratio and mechanical milling time. Compared with the alloys without mechanical milling, the yield strength of the as-SPSed alloys increases with the increase of mechanical milling energy, which reaches the highest value when the ball-to-powder weight ratio is 7.5:1.0 and the mechanical milling time is 100 h, increasing by about 19%, which is mainly due to the fine grain strengthening. The ultimate tensile strength tends to firstly increase and then decrease, which reaches the highest value when the ball-to-powder weight ratio is 7.5:1.0 and the mechanical milling time is 30 h, increasing by about 12%.

     

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