Microstructure and Chemical Composition Analysis of Additive Manufactured Ni-Mn-Ga Parts Sintered in Different Conditions

Abstract

Near-stoichiometric Ni 2 MnGa ferromagnetic shape memory alloys (FSMA) are known for producing a large magnetic field induced strain (MFIS's) in the presence of external magnetic fields. The MFIS's are in the order of 10% for single crystals [1] and 0.5% for polycrystalline Introducing porosity into polycrystalline Ni-Mn-Ga has shown an increase in MFIS's, resulting in a stable 4.5-5.1% MFIS These large MFIS's have attracted scientific and engineering interest, albeit the production and manufacturing of Ni-Mn-Ga is challenging due to the brittle mechanical properties, as well as the necessity to maintain a rigorous stoichiometry. Based on these recent discoveries, as well as current interest in advanced manufacturing, specifically additive manufacturing (AM), the capability to produce Ni-Mn-Ga porous parts of a desired geometry is presented. AM via binder jetting repeats the adhesion of metallic powder layers based on a CAD design, resulting in a porous near net shaped part. The purpose of this work is to examine material properties including microstructure, porosity, chemical composition, and crystallography of AM Ni-Mn-Ga parts which underwent different sintering conditions.