Production of Cu-Hf-Ti Bulk Glassy Composites by Mechanical Alloying and Spark-Plasma Sintering
This work reports on the production of Cu-Hf-Ti bulk glassy composites through a powder metallurgical route, i.e. by mechanical alloying and subsequent spark-plasma sintering. Powders of Cu60Hf30Cu10 and Cu60Hf25Ti15 composition were prepared using a high-energy planetary ball-mill. Both alloys nearly showed a fully amorphous structure with only a small fraction of residual HCP Hf grains left after 50 h of milling. Differential scanning calorimetry (DSC) analyses of the milled glassy powder revealed a two-stage crystallization process for both compositions. However, the released crystallization enthalpy was substantially larger for the Cu60Hf25Ti15 alloy than for the Cu60Hf30Ti10 alloy, suggesting that the former comprises a higher fraction of the amorphous phase than the latter. Both powders showed distinct glass-transition with a large super-cooled liquid region. Consolidation of Cu60Hf25Ti15 powder was carried out by means of spark-plasma sintering at applied pressures of 200 and 500 MPa, choosing a sintering temperature within the super-cooled liquid region (T = 753 K). The sintered compacts exhibited some pores and interparticle boundaries.
Jang Hyun Sung, Chan Gyu Lee, Yong Zoo You, Young Kook Lee and Jae Young Kim
P. P. Choi et al., "Production of Cu-Hf-Ti Bulk Glassy Composites by Mechanical Alloying and Spark-Plasma Sintering ", Solid State Phenomena, Vol. 118, pp. 655-660, 2006