富鎳鈦鎳形狀記憶合金箔帶之成分與時效處理對相變態溫度與機械性能之影響

Abstract

本研究使用熔旋噴鑄製程製備Ti50-xNi50+x(x=0.5、1、1.5、2)形狀記憶合金箔帶，結果顯示轉速、石英管開口口徑與噴出壓力影響箔帶的巨觀形貌與微觀結構。富鎳鈦鎳塊材由熔旋噴鑄製成箔帶後，無相變態行為發生，進行500 °C時效後產生B2→R→B19'與B19'→R→B2之二階相變態行為，且隨著時效時間增加，Ti3Ni4相的析出導致相變態溫度上升。500°C時效1小時的富鎳鈦鎳箔帶中，最大可回復應變在Ni50.5到Ni51.5從4.3%成長至4.5%，到Ni52時降低到3.0%，而Ni50.5到Ni51.5的理論彈熱溫降值從9.6°C成長至16.3°C，到Ni52時降低至8.8°C，其中Ni52的最大可回復應變與理論彈熱溫降值顯著降低是因為相變態溫度過低，在形狀記憶效應實驗可承受的最大應力下不足以產生完全的麻田散體相變態。四者之不可回復應變皆小於0.1%，擁有很好的形狀記憶效應。500°C時效1小時的富鎳鈦鎳箔帶中出現盤狀與透鏡狀之Ti3Ni4析出物，四種鎳含量下的析出物尺寸皆相近，約為100 nm，而隨著鎳含量上升，析出物的面積分率從20.3%增加到36.6%。此外，500 °C時效1小時的富鎳鈦鎳箔帶都有良好的熱循環穩定性，100次熱循環過程中，相變態溫度的變化皆在0.5～0.7°C以內。

In this study, the melt-spinning technique was employed to fabricate Ti50-xNi50+x(x=0.5、1、1.5、2)shape memory alloy ribbons. Results showed that the spinning speed, quartz tube diameter, and ejection pressure affect the macroscopic morphology and microstructure of the ribbons. Ni-rich TiNi bulk materials made into ribbons showed no phase transformation behavior until aged at 500°C, producing two-stage phase transformations: B2→R→B19' and B19'→R→B2. Increased aging time led to Ti3Ni4 precipitation, raising phase transformation temperatures. At 500°C for 1 hour, the maximum recoverable strain increased from 4.3% for Ni50.5 to 4.5% for Ni51.5, then decreased to 3.0% for Ni52. The theoretical elastocaloric temperature drop increased from 9.6°C for Ni50.5 to 16.3°C for Ni51.5, then decreased to 8.8°C for Ni52. The significant reduction in the maximum recoverable strain and theoretical elastocaloric temperature drop of Ni52 is due to the excessively low phase transformation temperature. At the maximum stress that can be sustained during the shape memory effect experiment, a complete martensitic transformation cannot occur. All four compositions had less than 0.1% irrecoverable strain. Disc- and lens-shaped Ti3Ni4 precipitates were about 100 nm in size, with area fractions increasing from 20.3% to 36.6% with higher Ni content. Additionally, ribbons aged at 500°C for 1 hour showed good thermal cycling stability, with phase transformation temperature variations within 0.5–0.7°C.