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Spark plasma sintering behavior of TaNbHfZrTi high-entropy alloy powder synthesized by hydrogenation-dehydrogenation reaction
Intermetallics ( IF 4.4 ) Pub Date : 2021-01-02 , DOI: 10.1016/j.intermet.2020.107077
Ki Beom Park , Jae-Young Park , Young Do Kim , Tae-Wook Na , Chan Bin Mo , Jong-In Choi , Jun Choi , Hyun-Su Kang , Hyung-Ki Park

In this study, we successfully synthesized TaNbHfZrTi high-entropy alloy (HEA) powders using a hydrogenation-dehydrogenation reaction and investigated their sintering behavior using a spark plasma sintering method. The initial ingot had a single solid solution body-centered cubic (BCC) phase, but after annealing in the hydrogen atmosphere, it absorbed hydrogen and transformed to a metal hydride phase. At this time, the brittleness was caused, making it easy to pulverize into powder; hydrogen in the powder was then removed through a vacuum heat treatment. The dehydrogenated powders had a dual-phase microstructure composed of several tens of nm sized BCC and hexagonal-close packed (HCP) phases. After sintering the HEA powders at 1000 °C, densification was completed though the HCP phase remained and the grain growth occurred non-uniformly. In the compact sintered at 1100 °C, a single solid solution BCC phase formed as the HCP phase disappeared and grain growth occurred uniformly to form an equiaxed microstructure. When comparing the microstructures, the grain size of the initial ingot was 227.8 μm, but it significantly decreased to 22.5 μm in the compact sintered at 1100 °C. To analyze mechanical property changes induced by adopting the powder metallurgy method, compression tests were carried out. For the ingot, the yield strength was 1119 MPa, but the yield strength of the sintered compact increased to 1677 MPa due to the grain size refinement effect.



中文翻译:

氢化-脱氢反应合成的TaNbHfZrTi高熵合金粉末的火花等离子体烧结行为

在这项研究中,我们成功地通过氢化-脱氢反应合成了TaNbHfZrTi高熵合金(HEA)粉末,并使用火花等离子体烧结法研究了它们的烧结行为。最初的铸锭具有单一的固溶体心立方(BCC)相,但在氢气氛中退火后,它吸收了氢并转变为金属氢化物相。此时,引起脆性,容易粉碎成粉末。然后通过真空热处理除去粉末中的氢。脱氢粉末具有由数十纳米大小的BCC和六方密堆积(HCP)相组成的双相微观结构。将HEA粉末在1000°C下烧结后,尽管保留了HCP相,但致密化完成,并且晶粒生长不均匀。在1100℃下烧结的成形体中,随着HCP相的消失而形成单一的固溶BCC相,晶粒的生长均匀地发生,从而形成等轴组织。比较显微组织时,初始铸锭的晶粒尺寸为227.8μm,但在1100°C的烧结体中,晶粒尺寸显着减小至22.5μm。为了分析采用粉末冶金法引起的机械性能变化,进行了压缩试验。对于铸锭,屈服强度为1119MPa,但是由于晶粒细化效果,烧结体的屈服强度增加至1677MPa。初始铸锭的晶粒尺寸为227.8μm,但在1100°C烧结的压坯中,晶粒尺寸显着减小至22.5μm。为了分析采用粉末冶金法引起的机械性能变化,进行了压缩试验。对于铸锭,屈服强度为1119MPa,但是由于晶粒细化效果,烧结体的屈服强度增加至1677MPa。初始铸锭的晶粒尺寸为227.8μm,但在1100°C烧结的压坯中,晶粒尺寸显着减小至22.5μm。为了分析采用粉末冶金法引起的机械性能变化,进行了压缩试验。对于铸锭,屈服强度为1119MPa,但是由于晶粒细化效果,烧结体的屈服强度增加至1677MPa。

更新日期:2021-01-04
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