Static mechanical characterization of a bulk amorphous and nanocrystalline Zr40Ti14Ni11Cu10Be25 alloy

Bulk amorphous samples of a Zr40Ti14Ni11Cu10Be25 alloy were tested in compression at displacements rates from 10(-4) s(-1) to 10(-1) s(-1). No dependence ofYoung's modulus on strain rate was found. There was, however, a change in modulus on repeated cycling the load because of relaxation effects, up to a steady value of 102 GPa. Ductility was very limited since a maximum plastic strain at fracture of 1% was reached. The tensile strength was 2 CPa. Vein patterns due to strain localization were observed on fractured surfaces. Partially crystallized samples contained a nanocrystalline phase. The hardness increased with an increasing amount of nanocrystalline phase. The toughness decreased to values of 1-2 MPa root m as in brittle ceramics due to loss of intrinsic ductility of the amorphous matrix. Fracture surfaces displayed typical brittle behavior. The possibility of avoiding strain localization in the amorphous phase is discussed. (C) 1997 Acta Metallurgica Inc.