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Research on Synthesis and Property of the Ultrafine Grain and Nanocrystalline Ti-Al Alloy

Author: KangKai
Tutor: ChenHua
School: Changchun University of
Course: Materials Physics and Chemistry
Keywords: TiH2-Al-Nb alloys High - energy mechanical milling Liquid phase sintering High temperature oxidation resistance Ultrafine grain / nanocrystalline group
CLC: TF124.5
Type: Master's thesis
Year: 2011
Downloads: 45
Quote: 0
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Abstract


Advanced design concepts are often higher use temperature , lighter , and run faster based , and titanium - aluminum intermetallic compound TiAl - based intermetallic compound is most likely to satisfy the design requirements described above , is considered to be the most the application potential of a new generation of lightweight high temperature structural materials , is expected to be widely used in aviation, automotive industry and other parts of the production . Ductility at room temperature and high temperature oxidation resistance of γ-TiAl intermetallic compounds the problem of insufficient , limiting its use and development . The purpose of this test is using the powder mechanical alloying and sintering method , the synthesis and preparation of ultrafine grain / nanocrystalline γ-TiAl organization , and to study the performance of their organizations . The test is a single element powder mixing method , the choice of TiH2 , Al and the Nb powder , preparation of TiH2-47Al-(5-12) Nb ingredients alloy , formed by milling the amorphous-containing Ti2A1 metastable equal nanoscale particles powder by DSC and spark plasma sintering method , the various process milled powder the vacuum sintering protective atmosphere sintering to obtain the ultrafine grain / nanocrystalline γ - TiAl based two-phase TiAl fund intergeneric compounds . By means of scanning electron microscopy , X-ray diffraction (XRD) , transmission electron microscopy , differential thermal analyzer , observe and analyze the process of change of the phase transition in the synthesis of powders by mechanical alloying and sintering using the DSC control oxidizing atmosphere research TiAl ultrafine grain structure The high temperature oxidation resistance . The test results show that : the high-energy ball milling pre- synthesis part amorphous TiAl between Asia , the nanoscale metastable phase is more conducive to sintering to form ultrafine grain / nanocrystalline TiAl intermetallic compounds block . Because the portion of the fine Al element is retained in the milled powder , while the lower melting point of Al , and thus the sintering occurs first liquefied , Al diffusion and the phase change to form the grain boundary high connecting strength . 1200 ° C for 10 minutes at sintering to produce ultrafine grained / nanocrystalline spherical TiAl and Ti3Al, . DSC sintering and spark plasma sintering of ultrafine grain structure containing nanocrystals , such a fine grain structure with a high temperature oxidation resistance . The oxidation rate of the alloy in the air is much less than the oxidation rate in the oxygen the Nb amount of increase is conducive to the improvement of the antioxidant . Confirmed by DSC cyclic oxidation alloys at elevated temperatures , high temperature insulation and cooling stage of the oxidation reaction , but the cooling phase oxidation .

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CLC: > Industrial Technology > Metallurgical Industry > Metallurgical Technology > Powder metallurgy (metal ceramic technology ) > Powder molding, sintering and post-processing > Sintering process
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