IN-SITU FORMATION OF NbC IN MECHANICALLY ALLOYED Cu-Nb-C AT DIFFERENT TEMPERATURES

摘要

In this study, a high-energy ball milling called mechanical alloying was applied to synthesis in- situ copper-based composite reinforced with niobium carbide particle. Cu, Nb and graphite powder mixture were mechanically alloyed for 32 h in a planetary ball with composition of Cu-11.77 %Nb-1.52 %C. The samples of the as-milled powder were compacted at 300 MPa to produce 10 mm diameter pellets. In order to investigate the effect of temperature on the carbide formation, the green compact were sintered in an argon atmosphere at different sintering temperature i.e. 600, 700, 800 and 900 °C. The change of phase and micro-structure of the sintered compact were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The result from XRD shows that the NbC phase was not detected at sintering temperatures lower than 900 °C due to not having enough energy to initiate the reaction of Nb and C in Cu matrix. Cu shows an increase in the crystallite size while the internal strain decreases with increasing sintering temperature. The crystallite size of NbC was unresolved since the NbC peak is poorly defined at lower sintering temperature. From EDX analysis, higher oxide content was observed in Cu matrix at higher temperature which retards the sintering process.