高性能航太渦輪引擎用耐熱合金之開發

Development of Heat-Resistant Alloys Used in High Performance Aerospace Turbine Engine

簡賸瑞(Sheng-Rui Jian) ； 邱茂盛(Mao-Sheng Chiu) ； 郭振明(Chen-Ming Kuo)

《科儀新知》 202期 (2015/03) Pp. 79-98

摘要

本研究首先以設計先進的方向晶鎳基超合金為目標，實驗方法包含計算模擬和實際實驗。以CM247LC之成份為基礎，並調整其材料參數，如晶格常數差、有序結構析出相、碳化物強化相及相穩定性來改善合金系統。在第一階段進行合金設計，使用CALPHAD基JMatPro來計算TTT曲線、晶格常數差及拉伸性能的預測；使用Thermal-Calc計算Al activity，以探討抗氧化之特性。第二階段將合金設計軟體Thermal-Calc計算改良之成份製成樣品，並進行高溫特性的分析。實驗內容包含兩部份，(1)Al元素的添加，(2)固溶熱處理之冷卻速率對高溫潛變特性的影響。由高溫氧化實驗中可得知，Al含量增加1 wt%，對其γ'析出相體積分率及抗氧化性有著顯著的影響，且在高溫氧化後機械性質可能也有著直接的影響。而在熱處理的實驗中可得知，固溶熱處理過程的冷卻速率對於後續時效γ'析出相成長尺寸及形狀的影響，直接反應在抵抗潛變強度上。

並列摘要

This report contains two research methodologies being conducted in parallel to design an advanced DS Nibased superalloy, i.e. through computer simulation and practical experiments. We have used CM247LC as the base alloy to further improve its alloy chemistry by adjusting its materials parameters such as lattice misfit, volume fraction of ordered precipitates, volume fraction of carbide strengtheners, and phase stability. Alloy design has been conducted in this stage; Calphad-based JMatPro has been utilized to calculate the TTT curves, lattice misfit as well as predictions for its tensile properties；Thermal-Calc was used to calculate Al activity to rationalize the oxidation resistances. In the second stage, specimens were prepared through the composition improvements by alloy design software Thermal-Calc and high temperature properties were evaluated. Experiment work includes (1) addition of Al element, (2) effects of solution heat treatment cooling rates. From high temperature oxidation test results, with 1wt% Al addition, the gamma prime volume fraction and oxidation resistance are improved significantly. In addition, the mechanical properties after high temperature oxidation are also influenced very note worthily. The effect of solution heat treatment cooling rates can affect the size and shape of gamma prime greatly, which have very strong effects on the high temperature creep properties of superalloys.