Abstract TixAlCoCrFeNi2.1(x = 0, 0.1, 0.15, 0.2) high entropy alloys (HEAs) were obtained by vacuum arc melting followed by suction casting. The influences of traces of Ti addition on the microstructure morphology, average phase fraction, phase orientation relationship (OR) were investigated employing X-ray diffraction (XRD), scanning electron microscopy (SEM) equipped with energy-dispersive spectroscopy (EDS), electron-probe microanalyzer (EPMA), electron back-scattered diffraction (EBSD), transmission electron microscope (TEM). Tensile tests were conducted. Results reveal that microstructures show a morphology transition from lamellae to petal after adjunction of Ti, forming a dual phase of L12 and B2. Strict K–S OR, namely, {111}FCC//{011}B2, FCC// B2 between lamellar microstructure has been verified, while the petal-like microstructure deviates from such OR. Cr-rich nano-particles with different morphologies inside the B2 phase are coherent with B2 matrix for Ti0.15AlCoCrFeNi2.1 alloy. With the increase of Ti content, ultimate tensile strength (UTS) and elongation increase firstly and subsequently decrease till with 3.17 at.% (x = 0.2) Ti addition. The as-cast Ti0.15AlCoCrFeNi2.1 alloy exhibits a well combination of UTS (1253 MPa) and acceptable ductility (12.9%), which can be attributed to the balance of L12 and B2 phases as well as the precipitation of Cr-rich nano-particles inside the B2 phase.

中文翻译：

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Ti添加量对AlCoCrFeNi2.1共晶高熵合金组织和拉伸性能的影响

摘要 TixAlCoCrFeNi2.1(x = 0, 0.1, 0.15, 0.2) 高熵合金（HEAs）是通过真空电弧熔炼和抽吸铸造获得的。采用 X 射线衍射 (XRD)、配备能量色散谱 (EDS)、电子显微镜 (SEM) 的扫描电子显微镜 (SEM) 研究了微量 Ti 添加对微观结构形貌、平均相分数、相取向关系 (OR) 的影响。 -探针显微分析仪 (EPMA)、电子背散射衍射 (EBSD)、透射电子显微镜 (TEM)。进行了拉伸试验。结果表明，在加入 Ti 后，微观结构显示出从片状到花瓣的形态转变，形成 L12 和 B2 的双相。严格的K-S OR，即{111}FCC//{011}B2、FCC// B2在层状微结构之间已经得到验证，而花瓣状的微观结构则偏离了这种 OR。对于 Ti0.15AlCoCrFeNi2.1 合金，B2 相内部具有不同形貌的富铬纳米颗粒与 B2 基体相结合。随着Ti含量的增加，极限抗拉强度(UTS)和伸长率先增加后降低，直到Ti添加量为3.17 at.% (x = 0.2)。铸态 Ti0.15AlCoCrFeNi2.1 合金表现出良好的 UTS (1253 MPa) 和可接受的延展性 (12.9%)，这可归因于 L12 和 B2 相的平衡以及富铬纳米晶的析出-B2 相内的颗粒。极限拉伸强度 (UTS) 和伸长率首先增加，然后降低，直到添加 3.17 at.% (x = 0.2) Ti。铸态 Ti0.15AlCoCrFeNi2.1 合金表现出良好的 UTS (1253 MPa) 和可接受的延展性 (12.9%)，这可归因于 L12 和 B2 相的平衡以及富铬纳米晶的析出-B2 相内的颗粒。极限拉伸强度 (UTS) 和伸长率首先增加，然后降低，直到添加 3.17 at.% (x = 0.2) Ti。铸态 Ti0.15AlCoCrFeNi2.1 合金表现出良好的 UTS (1253 MPa) 和可接受的延展性 (12.9%)，这可归因于 L12 和 B2 相的平衡以及富铬纳米晶的析出-B2 相内的颗粒。