| Powder metallurgy (PM) method is thought to be a suitable process to fabricate metalmatrix composite for the advantages such as near net shape, accurate componentproportion and low precess temperature. However, conventional PM process often needlong sintering time, which result in grain coarsening and poor performance of mechanicalproperities. Microwave sintering is a newly developed sintering method which presentsdistinct advantages such as volumetric heating, increased heating rate and decreasedholding time. Attributed to these advantages, the microwave strcture and mechanicalproperities of sintered composites can be significantly improved.In this paper, microwave sintering was adopted to fabricate Al/(Ti,W)C composites.The effect of sintering temperature and (Ti,W)C amount have on macro appearance, grainsize, distribution of (Ti,W)C, porosity, interface characteristic, microhardness andcompressive properity were studied by use of scanning electron microscopy (SEM),energy dispersive spectrometer (EDS), X-ray diffraction (XRD), microhardness test andcompressive test. The mechinal of microwave heating metallic materials and strengthenmechanism of the composite were investigated.The results show that Al/(Ti,W)C composites could be fabricated by microwavesintering at low sintering temperature and in short holding time. Small grain size anduniform distribution of (Ti,W)C were obtained. The sintering temperature and (Ti,W)Ccontent have a great influence on mivrostructure and mechanical properities. The relativedensity was decreased with an increase in the additive amount of (Ti,W)C particulates,firstly decreased and then increased with an increase in sintering temperature. Grain sizegrowth trend was readily controlled and small grain size was obtain owing to the additionof (Ti,W)C phase. On the contrary, the grain size was increased with the increase ofsintering temperature. The interfaces in Al/(Ti,W)C composite (Al/Al,(Ti,W)C/(Ti,W)C,Al/(Ti,W)C) were found with no reaction and gap–free. Mechanical tests indicated that theaverage microhardness, compressive yield strength as well as compression strength wereenhanced with an increase in both (Ti,W)C particulate amount and sintering temperature(range from520°C to560°C). Raising sintering temperature from500℃to520℃has no significant influence on mechanical properties. Mechanism of interface bonding was solidstate diffusion along with a small amount of liquid phase sintering. The mainstrengthening mechanism is refined crystalline strengthening and dispersion strengthening. |
PDF Full Text Request