Thermal and transport properties of Ni2MnGa1−xAlx alloys

• DOI: 10.1016/j.intermet.2010.06.014
• Publication Date: 2010-07-16T05:29:49Z
• Authors: A.C. Abhyankar; Y.T. Yu; Y.K. Kuo; G.W. Huang; C.S. Lue
• Keywords: Substitution (logic); Diffusionless transformation

Abstract A series of Ni 2 MnGa 1− x Al x ( x = 0, 0.03, 0.05, 0.10, 0.15 and 0.20) alloys are studied by means of electrical resistivity, ρ ( T ), Seebeck coefficient, S ( T ), thermal conductivity, κ ( T ), as well as specific heat measurements. It is observed that the martensitic transition temperature show a significant but complex variation for the low level of partial Al substitution with respect to Ga whereas magnetic ordering temperature is little affected. However, upon increasing Al content ( x ≥ 0.10), a drastic suppression of the martensitic transition along with a gradual broadening/suppression of the magnetic ordering take place. Such observations are in sharp contrast to the general expectation for the nonmagnetic and isoelectronic Al substitution with respect to Ga. X-ray diffraction studies revealed that increase in Al substitution leads to the formation of B 2 phase and which plays an important role on the martensitic and magnetic transition characteristics and physical properties of Ni 2 MnGa 1− x Al x alloys.