Structural and magnetic properties of Co2CrAl Heusler alloys prepared by mechanical alloying

Mechanical alloying has been used to produce nanocrystalline samples of Co2CrAl Heusler alloys. The samples were characterized by using different methods. The results indicate that, it is possible to produce L2(1)-Co2CrAl powders after 15 h of ball-milling. The grain size of 15 h ball milled L2(1)-Co2CrAl Heusler phase, calculated by analyzing the XRD peak broadening using Williamson and Hall approach was 14 nm. The estimated magnetic moment per formula unit is similar to 2 mu(B). The obtained magnetic moment is significantly smaller than the theoretical value of 2.96 mu(B) for L2(1) structure. It seems that an atomic disorder from the crystalline L2(1)-type ordered state and two-phase separation depresses the ferromagnetic ordering in alloy. Also, the effect of annealing on the structural and magnetic properties of ball milled powders was investigated. Two structures were identified for annealed sample, namely L2(1) and B2. The obtained value for magnetic moment of annealed sample is smaller than the as-milled sample due to the presence of disordered B2 phase and improvement of phase separation. (C) 2010 Elsevier B.V. All rights reserved.