Formation range, thermal and mechanical properties of amorphous phase in liquid quenched Al_(100-(X+Y))Ni_xMm_Y ((X+Y)≤20at%) alloys were investigated. Mixed phases of (Al+comp) and (Al+Am) were obtained in the range of (Ni+Mm)≤6at% and 6at%≤(Ni+Mm)≤10at%, respectively. Amorphous single phase was formed in the range of 10at%≤(Ni+Mm)≤20at%. An onset temperature(Tx) for crystallization of amorphous phase increased with increasing (Ni+Mm) content, indicating an enhancement of the thermal stability. Glass transition phenomenon was occurred in the composition of Al((90-x))Ni_(10)Mm_x (X=5-10at%) and Al_((92-x))Ni_8Mm_x (X=6-10at%). Tensile fracture strength(σ_f) and hardness(H_v) for the mixed phase alloys of (Al+Am) showed higher values than those of other phases. In the amorphous single phase region, σ_f and H_v increased with solute (Ni+Mm) content. The strengthening was presumed to be caused by an increase of Al-Ni or Al-Mm atomic pairs with strong bonding nature in the amorphous matrix. (Received September 1, 1998)