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

• Main Authors: I. Unzueta, J. López-García, V. Sánchez-Alarcos, V. Recarte, J. I. Pérez-Landazábal, J. A. Rodríguez-Velamazán, J. S. Garitaonandia, J. A. García, F. Plazaola
• Format: Article
• Language: English
• Published: MDPI AG 2021-03-01
• Series: Metals
• Subjects: metamagnetic shape memory alloys; structural defects; ¹¹⁹Sn Mössbauer spectroscopy; internal stress
• Online Access: https://www.mdpi.com/2075-4701/11/3/450

The influence of both the Co addition and the internal stress on the atomic level magnetism is comparatively studied in Ni<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mrow></mrow><mn>50</mn></msub></semantics></math></inline-formula>Mn<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mrow></mrow><mn>37</mn></msub></semantics></math></inline-formula>Sn<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mrow></mrow><mn>13</mn></msub></semantics></math></inline-formula> and Ni<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mrow></mrow><mn>45</mn></msub></semantics></math></inline-formula>Mn<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mrow></mrow><mn>38</mn></msub></semantics></math></inline-formula>Sn<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mrow></mrow><mn>13</mn></msub></semantics></math></inline-formula>Co<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mrow></mrow><mn>4</mn></msub></semantics></math></inline-formula> alloys by magnetic measurements and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mrow></mrow><mn>119</mn></msup></semantics></math></inline-formula>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 <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mrow></mrow><mn>119</mn></msup></semantics></math></inline-formula>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 <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mrow></mrow><mn>119</mn></msup></semantics></math></inline-formula>Sn a powerful technique for the characterization of the stress present in Sn containing metamagnetic shape memory alloys.