Mechanical properties of Zr-based bulk glassy alloys containing nanoscale compound particles

For the last decade, bulk glassy alloys have been developed in a number of multicomponent alloy systems and have already gained practical applications. Although the bulk glassy alloys in Zr-based systems have high strength and good toughness, it has been found that the addition of special elements to the Zr-based glassy alloys causes the formation of a nanoscale mixed structure consisting of nanoscale intermetallic particles embedded in a glassy matrix and the mixed phase alloys exhibit higher mechanical strength and larger elongation as compared with the corresponding glassy single phase alloys. In particular, the bulk nanoscale mixed phase alloys in the Zr-Al-Ni-Cu-Nb system produced by squeeze casting exhibit extremely high bending flexural strength of 4400 MPa without fracture during the three point bending test. The mechanism for the formation of the nanoscale mixed structure for the alloys containing special additional elements as well as the reason for the remarkable improvement in the mechanical properties has been discussed on the basis of experimental results obtained by high-resolution TEM, nanobeam EDX spectroscopy, atom probe FIM and small angle X-ray scattering, in addition to DSC, ordinary TEM and X-ray diffraction. (C) 2000 Elsevier Science Ltd. All rights reserved.