Ti-Containing Zr Based Bulk Amorphous/Nanocrystalline Composite Alloys

Abstract

DSC curves show that the crystallization reactions change from a single exothermic peak to two exothermic stages by adding Ti up to 5 at% to Zr–Ni–Cu–Al amorphous alloys and bulk amorphous composites containing nanocrystalline particles were produced by annealing cast Zr70−x−yTixNi10Cu20Aly (x=5–7.5 and y=10–15 at%) amorphous alloys. The microstructure after the precipitation of a primary crystalline phase consists of the crystals less than 10 nm in size embedded in the amorphous matrix. Both the compressive strength and plastic strain increased significantly with increasing volume fraction of nanocrystals, and the maximum plastic strain was obtained in the early stage of nanocrystallization. High-resolution electron microscopy showed that the bulk nanocrystalline Zr53Ti5Ni10Cu20Al12 alloy with the maximum plastic strain includes nanocrystals with a much smaller grain size of about 2.5 nm.