單方向凝固超合金高熵化之高溫潛變及氧化特性之研究

Study on the High-Temperature Creep and Oxidation Behavior of Directionally Solidified Superalloy of High Entropy

黃健安(Chien-An Huang)

指導教授 ： 簡賸瑞

義守大學/理工學院/材料科學與工程學系/碩士(2016年)

摘要

本研究以高熵超合金為材料基礎，利用合金設計的觀點來開發成本
較低但性能優異的新型態耐熱合金材料。在鎳基超合金加入高熵效應，
使之變成高熵超合金(HESA-6/A/C)，其中HESA-A 以鎳(Ni)作為基底，添加八種不同元素其中2wt.%的鉭而沒有鈮；而HESA-C 只添加2wt.%的鈮而沒有鉭。試棒進行單方向凝固鑄造及完整固溶及時效熱處理，並探討其高溫潛變(982C/159MPa)及高溫氧化(1000C 1hr/50hr/100hr)性質的影響與變化。研究結果顯示高熵超合金HESA-C 的γ'相析出最為整齊且體積分率最高，因此高溫潛變性質最好。高溫氧化後發現HESA-C 的晶界無沉淀析出層為最薄，且產生一層連續緻密性的Al2O3 氧化層進而提高了材料的抗氧化性能，故HESA-C 氧化性質最好。

關鍵字

高熵超合金 ； 單方向凝固 ； 高溫潛變 ； 高溫氧化

並列摘要

In this study, high-entropy superalloy was selected as a base material for alloy design in order to develop low cost but high performance new type of heat-resistant
alloys. High-entropy superalloys (HESA-6/A/C) were nickel-based superalloys incorporated with high-entropy effect, wherein nickel (Ni) is a base element in HESAA
with eight different elements additions in which 2wt.% tantalum without niobium, on the other hand, 2wt% of niobium were added in HESA-C but no tantalum.
Specimens were prepared through directionally solidified casting processes and full solid solution and aging heat treatments, thereafter high temperature creep tests
(982C/159MPa) were conducted and high temperature oxidation tests (1000C 1hr/50hr/100hr) were investigated. Results show that the γ' phase of high-entropy superalloy HESA-C is precipitated neatest and with maximum volume fraction, so as to the best high temperature creep behavior. After high temperature oxidation tests, the PFZ of HESA-C is the thinnest and a continuous dense oxide layer of Al2O3 is formed further to improve the oxidation resistance of the material, so that the oxidation behavior of HESA-C is the best among three high-entropy superalloys.

並列關鍵字

High-entropy superalloy ； Directional solidification ； High temperature creep ； High temperature oxidation

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