Ab-initio Calculation of Structural and Magnetic Properties of Annealed Cu2MnAl Heusler Alloy

Heusler alloys attracted considerable interest for their versatile magnetic properties. In this paper, Cu2MnAl Heusler Alloy samples were prepared with high vacuum melting furnace under the atmosphere of pure Argon. Then the samples were crushed and milled by planetary miller to get a uniform grading about 2 to 3 um thick. The milled powders were annealed under a mixed controlled atmosphere of pure Hydrogen and pure Nitrogen at different temperatures. The treated powders were characterized by X-ray diffraction (XRD) and vibrating sample magnetometer (VSM). The structural property of Cu2MnAl was calculated by ab-initio method. Different types of refined structures of Cu2MnAl with different element occupation ratios and different occupation sites were calculated and the XRD patterns of the corresponding structures were concluded. With the calculated results, the property of the annealed powers of Cu2MnAl was demonstrated. The Cu2MnAl achieved its maximum saturation magnetization (Ms) of 72emu/g and minimum coercive (Hc) at 200℃ annealing temperature with L21 ordered structure. Other phases like Al2Mn3 and Cu9Al4 were formed when annealed above 300℃, and the Ms of the material drops between 200℃ and 400℃ or above 700℃, but rises between 400℃ and 700℃with its crystallization increased.