| In this paper, different amount of Co and Nb addition of Cu48-xZr48Al4Co/Nbx amorphous alloy and composite materials are selected for the study.Each component of the ladder samples are prepared by arc-melting, selecting the samples of 3mm diameter,the effect of the different Co and Nb addition on microstructure, crystallization degree,compressive deformation behavior and nanoindentation of Cu48-xZr48Al4Co/Nbx amorphous alloy and composite is held.By optical microscopy, X-ray diffraction and transmission electron microscopy,analysis of the effects of different Co and Nb addition on microstructure of Cu48-xZr48Al4Co/Nbx amorphous alloy and composite is held. The study found that addition of Co and Nb on alloy can improve the degree of order and the precipitation of nanocrystals in the area about 10 nm.By differential scanning calorimetry(DSC),effect of Co and Nb addition on the crystallization degree of the alloy is analysed. Studies have shown that with the increase of Co and Nb addition, the volume fraction of crystallization increases. The addition of Co and Nb alloys have little impact to crystallization activation energy,determining the microscopic mechanism of Co and Nb alloys to facilitate crystallization is to control the crystalline phase grow up. However, the increase of Co and Nb content would reduce the alloy supercooled liquid temperature range, thereby reducing the thermal stability of the alloy, and ultimately reducing the glass forming ability, promoting alloy crystal formation.Through the study of amorphous alloy and composite materials at room temperature compressive deformation behavior,we found that in-situ precipitated crystal phase can greatly improve the compression deformation plasticity of the alloys,and a large number of cross-shear bands are found on the alloy fracture surface.Analysis found that mechanisms of improving the alloy plasticity is crystalline phase induce transition of shear zone from the extension of a single one style to cooperative extension style. Through Stress-strain curves analysis we found serrated flow phenomenon corresponding to the shear band nucleation and propagation. When the addition of Co and Nb are respectively 0.5% and 3.7%,the alloys have largest deformation ablility which is 11% and 4% respectively. Alloy exhibits a strain hardening during plastic deformation, suggesting that plastic deformation of the alloy has good stability.This paper also discussed the compressive deformation behavior of 2mm diameter amorphous alloy and composite,founding that for 2mm diameter alloy samples compared to 3mm diameter alloy samples exhibit some degree of compression plasticity. Effect of Co and Nb addition on compression plasticity of 2mm diameter sample was similar to the sample of 3mm diameter one:with the increase of Co and Nb addition,the compression platicity increas and then turn to reduce.Through the analysis of nano-indentation of amorphous matrix phase and crystalline to alloys which have 0.5%Co and 3% Nb addition,we found that the the deformation of amorphous matrix was similar to compression deformation, occurring serrated flow phenomenon during the loading process.In addition, during the experiment we found that the creep phenomenon occurs. Under all experimental conditions,the study have proved that creep can be divided into namely nonlinear instability creep and linear stability creep. The stress exponent of steady creep stage increased with the increasing of load levels, indicating the alloys had a low level of stability under high loads; According to test results, we found that the amorphous phase has a higher hardness and elastic modulus as compared to crystal, and the hardness and elastic modulus are influenced by loading conditions-under high load levels alloy exhibits higher hardness and elastic modulus. |
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