In situ TiB-reinforced Cu-based bulk metallic glass composites

Cu-based bulk metallic glass (BMG) composites containing in situ TiB particles were successfully fabricated. The reinforcing TiB particles with a size of 5-10 mu m are uniformly distributed in the amorphous matrix. The particles have a good bonding to the matrix with a reaction layer. The BMG composites exhibit an obvious ductility with a plastic strain of 2% for the 17.5 vol.% TiB sample due to the suppression of shear band propagation and the generation of multiple shear bands during compressive testing. The hardness of the materials is increased from Hv543 for monolithic BMG to Hv650 for 23.6 vol.% TiB-containing BMG composite. (c) 2006 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Effect of over-doped yttrium on the microstructure, mechanical properties and thermal properties of a Zr-based metallic glass

The effects of over-doped yttrium on the microstructure, mechanical properties and thermal behaviour of an oxygen-contaminated Zr51Cu20.7Ni12Al16.3 bulk metallic glass are studied systematically. It has been found that, when yttrium doping is beyond the optimum doping, the glass-forming ability enhancement effect induced by yttrium addition decreases and the mechanical properties are adversely affected. In this study, a new phase with an orthorhombic structure (a = 0.69 nm, b = 0.75 nm and c = 0.74 nm) is identified in the yttrium over-doped alloys. (c) 2006 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Enhanced glass-forming ability of a Zr-based bulk metallic glass with yttrium doping

A significant enhancement in glass formation in a newly developed Zr51Cu20.7Ni12Al16.3 alloy has been achieved by yttrium doping. With just 0.5 at.% yttrium doping, the critical diameter of the as-cast alloys for glass formation has been increased from 3 mm to at least 10 mm. In the undoped, large-sized alloys, massive oxygen stabilized crystalline phases are observed but disappear in yttrium doped alloys. Very small amounts of stable alpha-Y2O3 phases found in the yttrium doped alloys, and their negligible effect on the metallic glasses' properties, provide a superior solution to achieve metallic glasses with a high glass formability. (c) 2006 Elsevier B.V. All rights reserved.