探討利用氣體霧化法製備之AlCoCrFeNi高熵合金粉末性質之研究

Study on the Properties of Atomized AlCoCrFeNi High-Entropy Alloy Powder

在此篇研究中，利用氣體霧化法制備AlCoCrFeNi高熵合金粉末，探討退火熱處理對於相演變、晶體結構及機械性質之影響。藉由氣體霧化製備之初始粉末具球狀且元素均勻地分佈，為純BCC相，而經熱處理後析出FCC相和σ相。機械性質方面如：硬度，經熱處理後因析出強化，硬度有明顯地提高。而初始粉末在600℃下退火，並於此處發生了相變化FCC （Al-Ni）相開始析出，且退火溫度之提高將影響析出相之析出速率。然而在退火溫度達800℃下時σ（Fe-Cr）相開始析出。本研究探討在不同退火溫度下之高熵粉末其機械性質與晶格常數之影響。研究顯示隨退火溫度之提高，原子劇烈振動造成晶體結構變鬆散，晶格常數變大。故氣體霧化法制備之AlCoCrFeNi高熵合金粉末藉由不同溫度下進行退火熱處理調整其相之組成，因析出強化之效應改善其機械性質。

In this study, AlCoCrFeNi high entropy alloy (HEA) powders were fabricated by gas atomization process, and the effects of annealing heat treatment on phase evolution and mechanical properties were investigated. The as-atomized powders have pure BCC phase with a spherical shape and equal composition distribution, and then the FCC and sigma phase sequentially generated after annealing. The mechanical property such as hardness was evidently enhanced, which was caused by precipitation hardening effect. After the raw powders were annealed at 600℃, the FCC (Al-Ni) phase began to precipitate, the its phase intensity raised with the annealing temperature. Then, the sigma phase (Fe-Cr) formed as the annealing temperature reached 800℃. Both mechanical properties and lattice constant were influenced by heating effect. According to the results, the lattice became loose with the increasing temperature. In summary, the mechanical properties and phase constitutions of gas-atomized AlCoCrFeNi HEA powders can be adjusted via annealing process, resulting in precipitation hardening effect.