The phase stability and magnetic properties of the half-metal-type Co2Cr1-xFexAl alloy system were investigated. It was found that the occurrence of two-phase separation is unavoidable in a concentration range of less than x=0.4, leading to deviation of the saturation magnetic moments from the generalized Slater-Pauling line. The L2(1)-type phase becomes stable in a concentration range of more than x=0.7, where no half-metallic behaviors are present. Consequently, it is concluded that the most favorable concentration for applications to spintronic devices is located around x=0.4 in Co2Cr1-xFexAl alloys having the B2-type phase. (C) 2004 American Institute of Physics.