Effect of annealing on the martensitic transformation of a CoNiAl ferromagnetic shape memory alloy

CoNiAl system is a potential candidate for engineering applications because of its improved ductility over other ferromagnetic shape memory alloys. We have made a sample of CoNiAl alloy (Co37Ni35Al28) by arc melting and characterized it by X-ray diffraction, resistivity, susceptibility and magnetization measurements. The martensitic phase transitions have been investigated in both the as-prepared and annealed CoNiAl alloys. We show how the metallurgical modifications progress in the system from the as-prepared to the annealed state and how they modify the transformation temperatures.