Effects of alloying additions on Fe-Mn-Si shape memory alloys.

Abstract

Fe-Mn-Si alloys are shape memory alloys which makeuse of the Y -E Stress-induced martensitic transformation.In this study, we report the effects of alloying additions on the shape memory effect (SME)of these alloys. It was found that the Mstemperature, the N6el temperature (TN) and the volume of stress-induced martensite govern the SME. Through the optimization of these factors we found that new alloy systems such as Fe-28Mn-6Si-5Cr. Fe-20Mn-5Si-8Cr-5Niand Fe-1 6Mn-5Si-12C~5Nialloys could exhibit good SME along with goodcorrosion resistance And it was also found that the thermomechanical treatment which improved the SME in Fe-Mn-Si base system was also effective to improve the SME of these new systems.KEYWORDS: Fe-Mn-Si alloy; shape memory ferrous alloy; shape memory effect: stress-induced Y -E martensitic transformation; Mstemperature: N6el temperature (TN): the amount of i• phase; training effect 1.

Influência da refusão por plasma na microestrutura de um revestimento Fe-Mn-Cr-Si depositado por aspersão térmica arco elétrico sobre aço inoxidável ASTM A743-CA6NM

“…A formação de martensita e é provável nestas ligas devido a baixa energia de falha de empilhamento encontrada nesta liga, em decorrência da adição de Si e Mn [27]. Na Figura 7 é visualizado o perfil de composição química das amostras com menor corrente de refusão, 90A e 100-80A, e as duas últimas, referente as amostras com maior corrente, 130A e 180-80A.…”

Improvement of Oxidation Resistance of an Fe–Mn–Si–Cr Shape Memory Alloy by Annealing under Vacuum

“…4) The surface layers of the samples were characterized by EPMA, SIMS and XPS. The EPMA apparatus was used for analyzing the average chemical composition in the bulk and surface layer.…”

“…A sheet of an Fe-28 mass%Mn-6 mass%Si-5 mass%Cr (Fe-27 at%Mn-11 at%Si-5 at%Cr) alloy, which is a typical shape memory alloy, 4) was cut into pieces of approximate 5 mm  10 mm. These were lapped to a mirror surface and will be referred to as LA hereafter.…”

“…Therefore, the chemical composition of the alloys is modified by the addition of a small percentage of chromium in order to improve their oxidation and corrosion resistance. 4) The effect of chromium addition on the oxidation and corrosion resistance should be fully exploited for improving surface properties since the chemical composition in the surface layer may be modified by further treatment. For example, chromium is enriched to the surface of iron-chromium alloys by annealing under ultra high vacuum and the chromium-enriched layer is known to suppress the native oxide layer formed at room temperature.…”

Large recovery strain in Fe-Mn-Si-based shape memory steels obtained by engineering annealing twin boundaries

“…Unfortunately, Ti-Ni-based alloys are very expensive owing to their low productivity and the high-cost fabrication caused by the expensive alloy ingredients and their low cold workability 4 . Therefore, low-cost polycrystalline shape memory steels (SMSs), such as Fe-Mn-Si [5][6][7][8][9][10][11][12][13][14][15] , Fe-Ni-C 16 and Fe-Ni-Co-Ti [17][18][19] , have been developed. Recently, a major breakthrough in the superelasticity has been made in the polycrystalline SMSs.…”