Structure and properties of composites prepared from partially amorphous ZrCuNiTi and nanocrystalline silver

Alloys of composition Zr40Cu40Ni10Ti10 and Zr48,5Cu32.5Ni9Ti10 (in at.%) were ball milled for 40 h starting from elemental powders or melt spun from cast ingots. In both cases amorphous structure was obtained, however in the case of ribbons, larger crystals of Cu10Zr7 or Ni7Zr2 phases of size of a few hundred nm were observed. In the case of milled alloys much finer intermetallic phases such as Zr2Cu or Cu10Zr7 were identified within the amorphous matrix using X-ray diffraction or HRTEM. In both alloys DSC studies have shown higher crystallization temperature for the powder, than for the ribbon. It was explained by a different structure of preexisting intermetallic nuclei crystallizing in milled powders. The milled amorphous powder was also used as a matrix for composites containing 20% or 50% of nanocrystalline silver powder, prepared from silver powder by ball milling. The composites hot pressed at the same temperature as the amorphous samples show in some places very narrow transition phase enriched in silver containing also other elements of the amorphous phase. Composites containing more silver show lower hardness and strength, but exhibit a few percent of plastic deformation in the compression test. Scanning electron studies of deformed composite samples show crack initiation within the amorphous phase, not at the components interfaces.

► Ball milling or melt spinning amorphization of ZrCuNiTi near eutectic alloys.
► Different structure of intermetallic phases in ribbons and milled powder suggested as a reason for higher crystallization temperatures in the milled amorphous powders.
► Composites prepared from milled amorphous powders and nanocrystalline silver powder show compression strength between 600–750 MPa and are suggested as perspective electric contact materials.