鐵基形狀記憶合金離子氮化之研究

應用真空感應熔煉法配製Fe64Mn30Si6和Fe59Mn30Si6Cr5二種合金，進行離子氮化之表面改質，以分析氮化層（化合物層與擴散層）的組成及成因，並探討溫度與氮氫比對氮化層之影響。實驗結果顯示，鐵基記憶合金之氮化層厚度遠低於一般鋼材或其他鐵基合金，原因在於Mn與N形成緻密之錳氮化物Mn4N，阻礙了N原子向內擴散所致。在相同條件下，Fe59Mn30Si6Cr5之氮化效果明顯較Fe64Mn30Si6合金為佳。此外，改變溫度及氮氫比等氮化參數可有效控制氮化層之成分與厚度。

Both Fe64Mn30Si6 and Fe59Mn30Si6Cr5 shape memory alloys are prepared by VIM technique. The ion nitriding of the alloys is carried out to investigate the effects of temperature and H2/N2 ratio on the related properties. Experimental results show that because of the formation of the intensive Mn4N the nitrided layer of Fe-based shape memory alloys is thinner than other Fe-based alloys. Fe59Mn30Si6Cr5 is ion-nitrided more effectively than Fe64Mn30Si6 due to the presence of Cr. The thickness and composition of the nitrided layer can be controlled by changing ion-nitriding parameters.