The effect of Sn content on mechanical, magnetization and shape memory behavior in NiMnSn alloys

The effects of the composition alteration on the magnetization and shape memory behavior of Ni₅₀Mn_40-xSn_10+x (x = 0, 1, 2, 3) alloys were systematically investigated by thermal, magnetic and mechanical experiments. Phase transformation from ferromagnetic austenite to weakly magnetic martensite was observed during thermal cycling under magnetic field and transformation temperatures were decreased with increasing Sn (or decreasing Mn). Moreover, the saturation magnetization of martensite increased with Sn content. Ni₅₀Mn₄₀Sn₁₀ showed the recoverable strain of 2.1% during thermal cycling under 300 MPa and the reversible superelastic strain of 2% at 190 °C. Mechanical experiments exhibited that the largest compressive deformation of about 7% at 650 MPa occurred in Ni₅₀Mn₃₉Sn₁₁ while Ni₅₀Mn₄₀Sn₁₀ had fractured at 4% and 390 MPa at room temperature.