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The Research on the Behavior of the Plastic Deformation for Zr65Cu27.5Al7.5 Block Amorphous Alloy by Oxygen

Author: ChengYanYan
Tutor: ZhangChangJun
School: Chang'an University
Course: Materials Processing Engineering
Keywords: Bulk amorphous alloys Original cast structure Original free volume content Compressive plastic deformation The apparent activation energy
CLC: TG139.8
Type: Master's thesis
Year: 2009
Downloads: 75
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Abstract


Using industrial-grade sponge zirconium, zirconium iodide, high purity aluminum (99.99% purity), copper (purity 99.99%) and added to increase the oxygen content of the zirconium oxide as raw material, prepared by arc melting oxygenated respectively 0.06at% and 0.68 at% the two kinds Zr of 65 the Al of the Cu 27.5 7.5 ternary block bulk amorphous alloy ingot. Subsequently, in different melting under an atmosphere, respectively, through the copper mold casting method, the preparation of a series of different diameter of the columnar sample. By X-ray diffraction analysis (XRD) and transmission electron microscopy (TEM) observation confirmed the critical diameter of the prepared as 2mm, the type of the oxygen content of the alloy columnar specimen are completely amorphous; based on certain continuous heating with heating rate DSC curve analysis, the different sizes of the two alloys occurs below the glass transition temperature than the heat and temperature relationships in the structural relaxation time curve, the experimental results show that, with the increase in the size of the sample, the free volume in the alloy content. gradually reduced, while in the case of the same size, the high oxygen content and no reduction of the original content of the free volume in the amorphous alloy; the height to diameter ratio of 2 different sizes of the two alloys columnar specimens at room temperature quasi-static compression experiment, and to establish the appropriate engineering stress - strain curve. The results show that for the cast sample of the same size, the high oxygen content significantly reduced the compressive plastic. To further understand the impact of oxygen on the plastic deformation behavior of the alloys, 1.5mm diameter the two alloys columnar sample height to diameter ratio (H: D = 1.0), the the geometric suppression room temperature uniaxial quasi-static compression experiments, make it happen varying degrees of inelastic deformation. The results found in the compression process of plastic deformation, higher oxygen concentration of the free volume content of the alloy and the degree of increase of the shear band density is lower than the degree of increase of the free volume content and the shear zone in the lower oxygen content of the alloy density, oxygen strongly inhibited the accumulation of free volume and the expansion of the shear zone, the mechanism of oxygen-induced brittleness and lower oxygen atoms of the alloy movable sex-related. Atom movability can be characterized by crystallization of the apparent activation energy. Ribbon sample using different oxygen content in the the spin melt spinning prepared based on different heating rates under the DSC curve analysis using Kissinger method to obtain its prior crystallization peak and the primary crystallization peak temperature at The apparent activation energy. The results show that the higher oxygen content increased activation of the bulk amorphous alloys can reduce the mobility of atoms, delaying the start of the shear zone with the result that the bulk amorphous alloy brittle. Thus, we propose that the activation energy as evaluation parameters of the oxygen content in Zr-based bulk amorphous alloys room temperature ductility.

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CLC: > Industrial Technology > Metallurgy and Metal Craft > Metallurgy and Heat Treatment > The alloy learn with a variety of properties of alloys > Other special nature of the alloy > Amorphous alloy
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