(TiZrHf)(NiCoCu)系列擬二元高熵形狀記憶合金之麻田散體相變態行為與機械性質之研究

Research on Martensitic Transformation Behaviors and Properties of Pseudobinary (TiZrHf)(NiCoCu)-based High Entropy Shape Memory Alloys

陳躍今(Yue-Jin Chen)

指導教授 ： 陳志軒

國立臺灣大學/工學院/機械工程學研究所/碩士(2018年)

https://doi.org/10.6342/NTU201803832

摘要

本研究針對Ti40Zr10Ni40Co5Cu5、Ti30Zr20Ni30Co10Cu10、Ti25Zr25(NiCoCu)50五元合金與TiZrHfNiCoCu、(TiZrHf)50Ni25Co10Cu15、(TiZrHf)Ni30.5Co5Cu15六元合金進行研究，探討高熵性質對形狀記憶合金相變態之影響。研究結果顯示六種合金皆無法形成單相固溶體，而是產生單一固溶體與析出物之混合相。影響相變態溫度的主因由加入Co與Hf、Zr的多寡決定，Co會抑制相變態溫度，而Zr、Hf則會提高相變態溫度，其中五元合金Ti40Zr10Ni40Co5Cu5、Ti30Zr20Ni30Co10Cu10、Ti25Zr25(NiCoCu)50及六元合金TiZrHfNiCoCu不產生相變態，而(TiZrHf)50Ni25Co10Cu15與(TiZrHf)Ni30.5Co5Cu15有B19’麻田散體相變態產生，(TiZrHf)50Ni25Co10Cu15爐冷相變態溫度峰值與逆變態溫度峰值分別為-24.0 °C、8.9 °C，固溶處理後相變態溫度峰值升高至-0.3°C、40.6°C，而(TiZrHf)Ni30.5Co5Cu15爐冷相變態溫度與逆變態溫度則為156.2 °C、200.3 °C。兩者熱循環後相變態溫度下降，主要原因為母相與麻田散體相匹配性不佳，在熱循環過程中導入差排所導致。(TiZrHf)50Ni25Co10Cu15¬¬在固溶處理後形狀記憶效應性能提升，可回復應變提高，不可回復應變降低，在650MPa下分別為4.78%、0.38%。(TiZrHf)Ni30.5Co5Cu15為高溫形狀記憶合金，經由時效後可調整變態溫度，500°C時效處理10小時之後之可回復應變為0.35%、可回復應變比為74.47 %，比600°C 時效1小時的可回復應變0.17%、可回復應變比54.84 %好，形狀記憶效應較好。研究結果顯示，(TiZrHf)50Ni25Co10Cu15比富鎳之(TiZrHf)Ni30.5Co5Cu15有更佳的形狀記憶效應。

關鍵字

形狀記憶合金 ； 高熵合金 ； 形狀記憶效應 ； 麻田散體相變態 ； 時效熱處理 ； 析出物

並列摘要

The influence of high entropy effect on Ti40Zr10Ni40Co5Cu5, Ti30Zr20Ni30Co10Cu10, Ti25Zr25(NiCoCu)50, TiZrHfNiCoCu, (TiZrHf)50Ni25Co10Cu15 and (Ti16.5Zr16.5Hf16.5)Ni30.5Co5Cu15 alloys is discussed in this study. All of the alloys form the mixing phases of B2 solid solution and Ti2Ni-like precipitate rather than a single solid solution. The martensitic transformation temperature will decrease by adding cobalt and increase by adding zirconium and hafnium. Martensitic transformation can be observed only in (TiZrHf)50Ni25Co10Cu15 and (Ti16.5Zr16.5Hf16.5)Ni30.5Co5Cu15. The forward and the reverse transformation peaks of furnace-cooled (TiZrHf)50Ni25Co10Cu15 alloy are at -24.0 °C and 8.9 °C, and increase to -0.3 °C and 40.6 °C after solid-solution treatment, respectively. The forward and reverse transformation peaks of furnace-cooled (Ti16.5Zr16.5Hf16.5)Ni30.5Co5Cu15 are 156.2 °C and 200.3 °C. Due to the poor compatibility of austenite and martensite, dislocations are introduced in (TiZrHf)50Ni25Co10Cu15 and (Ti16.5Zr16.5Hf16.5)Ni30.5Co5Cu15 alloys during the thermal cycle, and thus their martensitic transformation temperatures decrease as the number of martensitic transformation increases. The shape memory effect of (TiZrHf)50Ni25Co10Cu15 is improved after solution treatment. Its reversible strain reaches 4.78% and irreversible strain is smaller than 0.38% under 650MPa. (Ti16.5Zr16.5Hf16.5)Ni30.5Co5Cu15¬ is a high temperature shape memory alloy and its transformation temperature can be adjusted by aging treatment. After 500 °C aging for 10 hours, the reversible strain and the reversible strain ratio are 0.35% and 74.47%, respectively, better than 0.17% and 54.84% after 600 °C aging for 1 hour. Finally, (TiZrHf)50Ni25Co10Cu15 has better shape memory effect than Ni-rich (Ti16.5Zr16.5Hf16.5)Ni30.5Co5Cu15¬ alloy.

並列關鍵字

Shape memory alloys ； High entropy alloys ； Shape memory Effect ； Martensitic transformation ； Aging ； Precipitate

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