Abstract Title
Processing of Ni-Mn-Sn Magnetic Shape Memory Alloys
Additional Funding Sources
This work was funded by the National Science Foundation through Project DMR-01710640.
Abstract
Superelastic strain of 4.9% obtained for Ni-Mn-Sn Magnetic Shape Memory Alloy (MSMA) raises interest in this alloy for application as magneto-mechanical energy harvesting device. We explore different compositions and heat treatments to obtain polycrystalline Ni-Mn-Sn MSMAs with magnetic field-induced superelasticity at room temperature. We annealed as-cast Ni-Mn-Sn alloys to reduce micro-segregation and secondary, interdendritic phases and to grow large grains. We analyzed the samples with optical microscopy, x-ray diffractometry, and energy-dispersive x-ray spectroscopy, vibrating sample magnetometer to determine grain size, phases present, chemical composition, chemical homogeneity and magnetization curves. Samples were cut through heat treated polycrystalline Ni-Mn-Sn alloys to obtain oligocrystalline wires with bamboo grain structure for magneto-mechanical experiments under rotating magnetic field. We found segregation of Mn and Sn with Ni homogeneously distributed in induction melted alloy, showing dendritic structure. The annealing treatment reduced the segregation of Mn and Sn, removed dendritic structure to a large extent and caused grain growth from about 500 micrometer to 4-5 millimeter.
Processing of Ni-Mn-Sn Magnetic Shape Memory Alloys
Superelastic strain of 4.9% obtained for Ni-Mn-Sn Magnetic Shape Memory Alloy (MSMA) raises interest in this alloy for application as magneto-mechanical energy harvesting device. We explore different compositions and heat treatments to obtain polycrystalline Ni-Mn-Sn MSMAs with magnetic field-induced superelasticity at room temperature. We annealed as-cast Ni-Mn-Sn alloys to reduce micro-segregation and secondary, interdendritic phases and to grow large grains. We analyzed the samples with optical microscopy, x-ray diffractometry, and energy-dispersive x-ray spectroscopy, vibrating sample magnetometer to determine grain size, phases present, chemical composition, chemical homogeneity and magnetization curves. Samples were cut through heat treated polycrystalline Ni-Mn-Sn alloys to obtain oligocrystalline wires with bamboo grain structure for magneto-mechanical experiments under rotating magnetic field. We found segregation of Mn and Sn with Ni homogeneously distributed in induction melted alloy, showing dendritic structure. The annealing treatment reduced the segregation of Mn and Sn, removed dendritic structure to a large extent and caused grain growth from about 500 micrometer to 4-5 millimeter.
Comments
W60