鈮添加對於Fe-30Mn-6Si-5Cr形狀記憶合金之效應

Abstract

本研究用真空電弧熔爐配製Fe-30Mn-6Si-5Cr、Fe-30Mn-6Si-5Cr-0.1Nb、Fe-30Mn-6Si-5Cr-0.5Nb 和Fe-30Mn-6Si-5Cr-1.0Nb形狀記憶合金，經過時效處理後，進行形狀記憶效應與顯微結構之分析，並針對形狀記憶效應最佳的Fe-30Mn-6Si-5Cr-0.5Nb合金進行熱機處理與形狀記憶訓練，以達到形狀記憶效應最佳化之研究。 實驗結果顯示，各種合金於500~900℃施行2小時的時效處理，可改善其形狀記憶效應。其中Fe-30Mn-6Si-5Cr-0.5Nb合金經過2小時700°C時效處理後有最高的形狀回復率90.83% 。再以最佳的Fe-30Mn-6Si-5Cr-0.5Nb合金做形狀記憶訓練，其形狀回復率隨著訓練次數而遞增，經5次形狀記憶訓練後即接近100%之形狀回復率。以Fe-30Mn-6Si-5Cr-0.5Nb合金利用冷輥壓做預應變，應變量分別為5% 和10%。其中以5%應變量之合金在700°C兩小時時效處理後形狀回復率最好。最後以Fe-30Mn-6Si-5Cr-0.5Nb合金進行5%預應變和700°C時效處理後，在600°C回復溫度做訓練，其形狀回復率隨著訓練次數而遞增，經4次形狀記憶訓練後即接近100%之形狀回復率。可得知合併時效處理、熱機處理與形狀記憶訓練，可以有效達到形狀記憶最佳化之效果。

In this study, Fe-30Mn-6Si-5Cr, Fe-30Mn-6Si-5Cr-0.1Nb, Fe-30Mn-6Si-5Cr-0.5Nb and Fe-30Mn-6Si-5Cr-1.0Nb shape memory alloys were prepared using the vacuum arc re-melting (VAR) technique. The Fe-30Mn-6Si-5Cr-0.5Nb alloy, which exhibits the best shape memory performance among these alloys, was then subjected to the thermo-mechanical treatments and shape memory training. The adding of 0.5wt% Nb followed by ageing at 700°C for 2 hours could make the recovery ratio rise up to 90.83%. The Fe-30Mn-6Si-5Cr-0.5Nb alloy, which exhibits the best shape memory performance, is then subjected to the shape memory training. The recovery ratios increase with increasing training cycles. The shape recovery ratio reaches ~100% in the fifth training cycle. Cold-working has been applied to Fe-30Mn-6Si-5Cr-0.5Nb alloy to fabricate the pre-strained 5% and 10% samples. The pre-strained 5% sample with aging at 700°C for 2 hours could exhibit a best shape recovery ratio. The Fe-30Mn-6Si-5Cr-0.5Nb alloy with a 5% pre-straining and 700°C aging was subjected to the shape memory training. The recovery ratio increases with increasing training cycles. After four training cycles, the recovery ratio is nearly 100%.