Artículos de revistas
Structural and magnetic characterization of the intermartensitic phase transition in NiMnSn Heusler alloy ribbons
Autor
JOSE LUIS SANCHEZ LLAMAZARES
HORACIO FLORES ZUÑIGA
DAVID RIOS JARA
CESAR FIDEL SANCHEZ VALDES
Carlos Garcia
Institución
Resumen
"Phase transitions and structural and magnetic properties of rapidly solidified Ni50Mn38Sn12 alloy ribbons have been studied. Ribbon samples crystallize as a single-phase, ten-layered modulated (10M) monoclinic martensite with a columnar-grain microstructure and a magnetic transition temperature of 308 K. By decreasing the temperature, martensite undergoes an intermartensitic phase transition around 195 K. Above room temperature, the high temperature martensite transforms into austenite. Below 100 K, magnetization hysteresis loops shift along the negative H-axis direction, confirming the occurrence of an exchange bias effect. On heating, the thermal dependence of the coercive field H-C shows a continuous increase, reaching a maximum value of 1017 Oe around 50 K. Above this temperature, H-C declines to zero around 195 K. But above this temperature, it increases again up to 20 Oe falling to zero close to 308 K. The coercivity values measured in both temperature intervals suggest a significant difference in the magnetocrystalline anisotropy of the two martensite phases."