Amorphous phase formation during spray forming of Al84Y3Ni8CO4Zr1 alloy

In this investigation the Al84Y3Ni8Co4Zr1 alloy has been processed by spray forming to investigate the potential of achieving substantial fractions of the amorphous phase in the biller. The alloy was prepared by spray metal f orming using the ratio of volumetric gas how rate to mass of metal how rate of 8.7 m(3)/kg. The resulting biller, weighting 2.1 kg, as well as the pow ders produced by the particles that had not hit the growing billet (overspr ay), were characterized by using X-ray diffractometry (XRD), differential s canning calorimetry (DSC), scanning electron microscopy (SEM) and transmiss ion electron microscopy (TEM). The powders had particles with spherical mor phology in the size range of few microns to 100 mum with the median particl e diameters about 20 +/- 1 mum The resulting billet contained only crystall ine phases nevertheless the powder was composed of about 40% volume fractio n of amorphous phase. This result indicates that the heating of the billet, by the heat release during solidification of the liquid and semi-solid par ticles was at temperature and for time enough for crystallization. (C) 2001 Elsevier Science B.V. All rights reserved.