Microstructure and mechanical properties of slowly cooled Zr–Nb–Cu–Ni–Al composites with ductile bcc phase

We report about the microstructure and the mechanical properties of slowly cooled Zr–Nb–Cu–Ni–Al alloys with a glassy or a nanocrystalline matrix and ductile bcc precipitates. These alloys exhibit significantly improved mechanical behavior compared to monolithic glass, because the in situ formed composite undergoes work hardening and plastic deformation prior to failure. Changes in composition and cooling rate lead to different volume fractions and dendrite sizes of the bcc phase and, hence, to different values of yield strength, elastic and plastic strain. The glassy or nanocrystalline structure of the matrix influences mainly the elastic strain limit of the composites. This opens the possibility of obtaining tailored mechanical properties and could extend the range of industrial applications of such materials.