Shape-memory effect and strengthening nb and n-doped Fe-Mn-Si-based alloy

• Published in: Metallurgical and materials transactions. A, Physical metallurgy and materials science Vol. 32A; no. 7; pp. 1621 - 1628
• Main Authors: Ariapour, A, Yakubtsov, I, Perovic, D D
• Format: Journal Article
• Language: English
• Published: 01-07-2001
• ISSN: 1073-5623

The Fe-Mn-Si-based shape-memory alloys (SMAs) generally suffer from low strength due to their austenitic matrix. It is known that nitrogen in solid solution can increase the strength of steels more than any of the major alloying elements. However, high nitrogen levels in solid-solution form can suppress the shape-memory effect (SME) in the Fe-Mn-Si-based SMA. To increase the strength of the Fe-Mn-Si-based SMA significantly, we have doped the alloy with both nitrogen and niobium. Niobium has great affinity for nitrogen and, thus, NbN-dispersed particles can be produced in the alloy by hot rolling. These particles prevent grain growth of the alloy and increase the strength of the alloy due to their small grain size, precipitation hardening, and nitrogen solid-solution strengthening. Concomitantly, the SME of the alloy is improved due to the large removal of the nitrogen from the solid solution upon incorporation into the NbN particle. (Author)