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Investigation of the Glass Forming Ability of Ti-Based Alloys

Author: WuChen
Tutor: WangRui
School: Harbin Institute of Technology
Course: Chemical Engineering and Technology
Keywords: Ti -based alloys Ti - Cu amorphous alloy First-principles Calculate the phase diagram to learn
CLC: TG139.8
Type: Master's thesis
Year: 2008
Downloads: 143
Quote: 0
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Abstract


Ti-based alloys and Ti-Cu binary system, with a first-principles and combined with some the basic thermodynamic methods and calculation of phase diagrams learning method, a binary system Ti-Cu metal room The nature of the compound, as well as its role in the crystallization process of amorphous alloy. And preliminary study based on glass-forming ability of Ti-Cu binary system. First-principles calculation of the stable compounds in the Ti-Cu binary system ground state energy, lattice constant, and elastic modulus. Compared with the experimental values ??obtained by using methods with higher accuracy. The calculated two metastable phase of CuTi and CuTi3 energy, and get their elastic modulus, the lattice constants and atomic coordinates in order to experimental data and the subsequent comparison. Made under the energy of the ground state of the Ti-Cu binary system with the ingredients curve by the ground state energy of the ingredients curve inferred Ti55Cu45 amorphous alloy crystallization product. On the basis of the results of first-principles calculation, the calculated phase diagram to learn to re-optimize the thermodynamic parameters of the binary system Ti-Cu, obtained the phase diagram of the binary system. First, a large number of experimental data collected from the literature and some of the data is validated by differential thermal analysis, and has laid a good foundation for the subsequent optimization. Thereafter, on the basis of experimental data obtained by the above collection, the thermodynamic parameters of the Ti-Cu binary system is optimized to draw a new thermodynamic parameters. Finally, in the second step on the basis of the thermodynamic parameters of the Ti-Cu binary system, to make the phase diagram of the Ti-Cu binary system. Explicitly shown in the phase diagram may be present in the temperature range of L10 structure CuTi and Cu4Ti handled as an intermetallic compound, and some amendments near FIG CuTi3 original phase. Optimized on the basis of the phase diagram, a three-component alloy is selected in of CuTi and CuTi3 two-phase coexistence region study were: Ti58Cu42, Ti62Cu38 Ti54Cu46. The amorphous alloy thin strip obtained from 50 to 70 microns thick tungsten electrode EAF prepared by magnetron. Its thermodynamic properties by using a differential scanning calorimetry analysis, the results show that: the sample, an amorphous phase, and the proportion in the sample are larger. Meanwhile, in order to study the quantity and composition of the crystalline phase of the sample, using the X-ray diffraction to analyze the phase composition of the sample. The results show that: the thickness of about 50 microns Ti58Cu42, amorphous phase in a larger proportion; appeared in the 100 microns thick Ti58Cu42, more crystalline phase, the more obvious the precipitation phase: Cu3Ti, Cu4Ti3 and CuTi2 ; Similarly, for Ti62Cu38 amorphous alloys, increased thickness does not lead to more precipitation of crystalline phases; Ti54Cu46 XRD patterns, similar to the with Ti62Cu38 amorphous alloy, showed that the number of crystalline phases can not be with the amorphous phase relative to the number of comparison. Subsequently, in the vicinity of the eutectic point selected and prepared by methods of the three components of the amorphous alloy Ti55Cu45 Tongpan rejection band Ti57Cu43 and Ti60Cu40. Differential scanning calorimetry experiments: The results show that the three samples contained more amorphous phases. Been calculated more popular judgment Ti-based amorphous alloy glass forming ability criterion: reduction glass temperature Trg criterion and γ parameters, calculated results show that the three components of the alloy has a large glass-forming ability , indicating that the system evolved based ternary or system has a possibility of capable of producing the bulk metallic glass.

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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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