The Research On Glassy-forming Ability Of Cu-base Glassy Alloys

Bulk glassy alloys have a unique atomic property, which the atoms display a short-range ordered and long-range disordered. The material prepared by quenched the melting alloys with a fast rate. They exhibit many unique properties such as high strength, large elastic strain, high abrasive resistance and excellent corrosion resistance. At the same time bulk glassy alloy have been expected to be used in wide application fields, because they exhibit viscous flow workability in the supercooled liquid region. However the low glass formation ability and poor plasticity limit their use in industry. Therefore, in the present thesis the glass formation ability and mechanical properties of Cu-base glassy alloys are systematically investigated.The materials of Cu-Zr-Al alloy system first fabricated by a method of copper mould suction casting. The products were studied by X-ray diffraction、the differential thermal analytical and transmission electron microscope. The glass-formation ability by addition of minor rare earth Y and Ag in the Cu-Zr-Al alloy was discussed. The result as bellow:1. The investigated of Cu92-xZrxAly (x=36-47at.%、y=6-10at.%) alloys reveal that the content of Zr can improve the glass-forming ability, and the8at.%of Al is the best. The42-47at.%of Zr can prepare the glassy alloys with3mm in diameter; the Cu45Zr47Al8exhibit large glass-forming ability of5mm in diameter.2. The investigated of Cu47Zr45Al8-xAgx(x=2,4,6at.%) alloys find the fully glassy structure of Cu47Zr45Al4Ag4with the4.5mm in diameter.3. It was found that the addition of minor Y gieatly improved the glass-forming ability for Cu45Zr47Al8. Fully glassy alloy rods with diameters nearly10mm could be successfully fabricated using a copper mold casting method. The9mm rods with full glassy structure were obtained the (Cu45Zr47Al8)98Y2and (Cu45Zr47Al8)97Y3alloys.4.The Cu-Zr-Al alloys exhibit outstanding mechanical properties. The compressive fracture strength and plastic strain are increase when the content of Zr is increase; The47at.%of Zr in the Cu-Zr-Al alloys has a better plastic strain; The Cu47Zr47Al8alloy exhibit good plasticity of3.4%and high fracture strength of1929Mpa. The addition of minor Y into Cu47Zr45Al8alloys have led to decrease in hardness and improve in plasticity.5. The Cu65Zr35-xTix (x=5、10、15、20、25、30at.%) alloys fail to prepare amorphous materials. It was found that the addition of rare earth element of Y can improve the glassy-forming ability of the Cu60Zr30Ti10; Glassy alloy was fabricated by the alloy of (Cu60Zr30Ti10)98Y2.