Solid Solutions with bcc, hcp, and fcc Structures Formed in a Composition Line in Multicomponent Ir–Rh–Ru–W–Mo System
Solid Solutions with bcc, hcp, and fcc Structures Formed in a Composition Line in Multicomponent Ir–Rh–Ru–W–Mo System
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DOI：
10.2320/matertrans.mt-m2019212
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发表时间：
2019-11
影响因子：
1.2
通讯作者：
A. Takeuchi;T. Wada;H. Kato
中科院分区：
文献类型：
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作者：
A. Takeuchi;T. Wada;H. Kato
根据具有价电子浓度（VEC）的合金设计选择了五种Ir <$Rh <$Ru <$W <$Mo合金，研究了它们形成bcc、fcc和hcp结构的单相、双相和三相的情况。这些结构是用Thermo-Calc 2019 a和TCHEA 3数据库在沿着组成线的横截面相图上预测的：Ir0.415254（10012 x）Rh0.415254（10012 x）Ru0.169492（10012 x）WxMox（x：0 ~ 50 at%）。在T = 2100 K时，预测了四种类型的相：（1）在x = 35时，分别为单一的bcc、fcc和hcp相（合金A，VEC = 6.849），15（合金C，VEC = 7.981），和5（合金E，VEC = 8.574）;（2）bcc+hcp和hcp+fcc在x = 24时的混合物（合金B，VEC = 7.472）和8（合金D，VEC = 8.378）;（3）bcc+hcp+fcc的三元混合物;和（4）在低温下在合金A中的bcc+fcc的混合物。在2100 K下的实验表明，合金C和E具有更好的再现性，合金E可以被视为一种新的具有fcc结构的耐火高熵合金（HEA）。合金C在1273 K退火200 h后仍保持单一hcp结构。在Ir <$Rh <$Ru <$W <$Mo系统中，低温下不出现化学稳定相可类比地解释为缓慢扩散。具有hcp结构的HEAs的VEC分析被扩展，包括由4d和5d过渡金属组成的合金在其固相线温度附近退火的7.5 μ VEC ~ 8.4的范围。Ir <$Rh <$Ru <$W <$Mo系统在提供bcc、hcp和fcc相的所有可能的简单固溶体方面是重要的。[doi：10.2320/材料trans.MT-M2019212]
Five IrRhRuWMo alloys selected based on alloy design with valence electron concentration (VEC) were examined for their formation of single, dual, and triple phases of bcc, fcc, and hcp structures. These structures were predicted with Thermo-Calc 2019a and the TCHEA3 database on a cross-sectional phase diagram along a composition line: Ir0.415254(10012x)Rh0.415254(10012x)Ru0.169492(10012x)WxMox (x: 050 at%). At T = 2100K, four types of phases were predicted: (1) a single bcc, fcc, and hcp phase, respectively, at x = 35 (Alloy A, VEC = 6.849), 15 (Alloy C, VEC = 7.981), and 5 (Alloy E, VEC = 8.574); (2) a mixture of bcc+hcp and hcp+fcc at x = 24 (Alloy B, VEC = 7.472) and 8 (Alloy D, VEC = 8.378), respectively; (3) a triple mixture of bcc+hcp+fcc; and (4) a mixture of bcc+fcc in Alloys AE at low temperature. Experiments at 2100K revealed that Alloys CE tended to exhibit better reproducibility and that Alloy E can be regarded as a new refractory high-entropy alloy (HEA) with fcc structure. Alloy C annealed at T = 1273K for 200 h maintained a single-hcp structure. The non-appearance of thermodynamically stable phases at low temperature in the IrRhRuWMo system was analogically explained as slow diffusion. The VEC analysis for HEAs with hcp structures was extended by including the range of 7.5 ̄ VEC ̄ 8.4 for alloys consisting of 4d and 5d transition metals annealed near their solidus temperature. The IrRhRuWMo system was significant in providing all possible simple solid solutions of bcc, hcp, and fcc phases. [doi:10.2320/matertrans.MT-M2019212]