Synthesis and Mechanical Properties of Bulk Amorphous Zr–Al–Ni–Cu Alloys Containing ZrC Particles

Abstract

Bulk amorphous Zr 55 Al 10 Ni 5 Cu 30 composites containing ZrC particles up to 17 vol% were formed in a cylindrical form with diameters of 1 to 3 mm by a copper mold casting process. The average particle size and interparticle spacing of the ZrC particles are 3 and 4 μm, respectively, and neither distinct agglomeration nor segregation of the ZrC particles is seen on the transverse and longitudinal cross-sections. The glass transition temperature (T g ), crystallization temperature (T X ) and melting temperature (T m ) of the amorphous matrix remain unchanged in the volume fraction (V f ) range up to 17%. Neither appreciable second crystalline phase nor voids are seen even at the interface between the amorphous and ZrC phases, though the amorphous matrix has a relaxed disordered structure. The interface has a rugged morphology on a nanometer scale and does not have any faceted plane. The Young's modulus, compressive strength (σ f ) and Vickers hardness for the composite alloys increase almost linearly from 103 to 125 GPa and 1820 to 2170 MPa and 488 to 563, respectively, with increasing V f from 0 to 17%. The plastic elongation (e ρ ) also increases from nearly zero % at 0 vol% to 0.5% at 10 vol%. The significant increase in e ρ is presumably due to the increase in the amount of shear sliding before adiabatic final rupture resulting from the increase in σ f . The viscous flow of the supercooled liquid is also suppressed by the dispersion of the ZrC particles. The success in synthesizing the high-strength bulk composite alloys consisting of ZrC particles embedded in the amorphous matrix is important for future development of bulk amorphous alloys.