기계적 분쇄화 및 스파크 플라즈마 소결에 의한 TiAl 합금의 제조 = Research Fabrication of TiAl Alloys by Mechanical Milling and Spark Plasma Sintering

다국어 초록 (Multilingual Abstract)

In the present study, newly developed spark plasma sintering(SPS) technique was introduced to refine the grain size of γ-based TiAl intermetallic compounds. Ti-46AI-1.5Mo and Ti-46AI-1.5Mo-0.2C(at%) prealloyed powders were produced by mechanical milling(MM) in high-energy attritor. The mechanically milled powders were characterized by XRD and SEM for the microstructural evolution as a function of milling time. And then, the MMed powders were sintered by both spark plasma sintering and hot pressing in vacuum (HP). After the sintering process, MM-SPSed specimens were heat-treated in a vacuum furnace (SPS-VHT) and in the SPS equipment(MM-SPS) for microstructural control. It was found from microstrutural observation that the microstructure consisting of equiaxed γ-TiAl with a few hundred nanometer in average size and α₂-Ti₃Al particles were formed after both sintering processes. It was also revealed from hardness test and three-point bending test that the effect of grain refinement on the hardness and bending strength is much higher than that of carbon addition. The fully lamellar microstructures, which is less than 80㎛ in average grain size was obtained by SPS-VHT process, and the fully lamellar microstructure which is less than 100um in average grain size was obtained by MM-SPS for a relatively shorter heat-treatment time.

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