반응성 밀링에 의해 제조된 Cr₂O₃ 분산강화형 Cu 합금의 미세조직과 입자조대화 = The Microstructure and Coarsening Behavior of Cr₂O₃ Dispersoid in ODS Cu Produced by Reactive Milling

다국어 초록 (Multilingual Abstract)

Copper powder dispersed with 4 vol.% of Cr₂O₃ was successfully produced by a simple milling at 210 K with a mixture of Cu₂O, Cu and Cr elemental powders, followed by Hot Pressing (HP) at 1123 K and 50 MPa for 2h to consolidate the milled powder. The microstructure of the HPed material was characterized by standard metallographic techniques such as XRD (X-ray Diffraction), TEM and STEM-EDS. The results of STEMEDS analysis showed that the HPed materials comprised a mixture of nanocrystalline Cu matrix and Cr₂O₃ dispersoid with a homogeneous bimodal size distribution. The mechanical properties of the HPed materials were characterized by micro Vickers hardness test at room temperature. The thermodynamic considerations on the heat of formation, the incubation time to ignite MSR (Mechanically induced Self-sustaining Reaction), and the adiabatic temperature for the heat of displacement reaction between the oxide-metal are made for the delayed for mation of Cr₂O₃ dispersoid in terms of MSR suppression. The results of TEM observation and hardness test indicated that the relatively large dispersoids in the HPed materials are attributed to the significant coarsening for the high temperature consolidation; this leads to the low Vickers hardness value. Based on the thermodynamic calculation for the operating processes with a limited number of parameters, the formation kinetics and coarsening of the Cr₂O₃ dispersoid are discussed.
(Received June 14, 2018; Revised June 25, 2018; Accepted July 5, 2018)