Testing the Applicability of 119 Sn Mössbauer Spectroscopy for the Internal Stress Study in Ternary and Co-Doped Ni-Mn-Sn Metamagnetic Alloys.

The influence of both the Co addition and the internal stress on the atomic level magnetism is comparatively studied in Ni 50 Mn 37 Sn 13 and Ni 45 Mn 38 Sn 13 Co 4 alloys by magnetic measurements and 119 Sn Mössbauer spectroscopy. The results show that the saturation magnetization and the hyperfine field follow the same temperature trend. The internal stress state is investigated by subjecting the samples to milling and annealing treatments, and tracking the singlet component revealed by 119 Sn Mössbauer spectroscopy. Contrary to what was expected, in the Co-doped Ni-Mn-Sn sample the singlet component can be resolved between the milled and annealed states in both martensite and austenite phases. Therefore, the results demonstrate the feasibility of tracking the singlet component upon the structural recovery in Co-doped Ni-Mn-Sn alloys in a much wider range than in ternary alloys. In addition, it is concluded that the transferred dipolar field at Sn from the neighbor magnetic atoms depends very strongly on the stress field and on the microstructural order surrounding Sn atoms. The observed sensitivity of Sn Mössbauer probe atoms to slight microstructural distortions make 119 Sn a powerful technique for the characterization of the stress present in Sn containing metamagnetic shape memory alloys. [ABSTRACT FROM AUTHOR]