Thermal and mechanical properties of amorphous compound particles

The thermal and mechanical properties of an amorphous Zr₆₅Al_7.5Ni₁₀Cu_12.5Ag₅ alloy containing nanocrystalline compound phase were investigated. The Zr₃Al₂ phase with a spherical shape has a fine size of about 20 nm and is dispersed homogeneously at an interparticle spacing of about 30 nm in an amorphous matrix. The crystallization onset temperature and supercooled liquid regions decrease significantly with an increasing precipitation amount of Zr₃Al₂ phase, indicating an enhancement of thermal instability. This instability is presumably due to the change of the bonding nature among constituent atoms. The maximum tensile fracture strength (2070 MPa) of this mixed phase alloy is much higher than that (1200 MPa) for the amorphous single phase alloy with the same composition. Meanwhile, the good bending ductility of this alloy remains unchanged. Then, the fracture mode in the maximum tensile fracture strength was the shear type among the maximum shear plane. The significant increase of the tensile fracture strength is possibly due to the role of the nanoscale Zr₃Al₂ particles as an effective barrier to suppress shear sliding of the amorphous matrix.