Document Type : Research Article


Mechanical Department, The Federal University of Technology-Parana; Ponta Grossa, Parana; Brazil.


Semi-solid processing is a promising technique used to fabricate parts. The globular structure is the key in this process, a characteristic achieved with the partial melting material to temperatures between solidus and liquidus. In this sense, the aim of this research is to evaluate the microstructure quality of the aluminium matrix composite (AMC) reinforced with NbC, after semi-solid treatment. Micron-sized NbC powder was employed as reinforcement to fabricate a composite through the stir casting method. Furthermore, was used an Al-5Ti-1B alloy grain refinement. Globularization heat treatment at 562 °C, with a holding time of the 90s, was realized. An optical microscope under conventional and polarized light and a scanning electron microscope (SEM) allows the microstructure analyses. The dendritic cell size (DCS), grain size (GS), shape factor (SF), and rheo quality index (RQI) were used to analyse the morphology and microstructure. The results show a general reduction of GS and DCS and more globular microstructure parameters with a higher amount of NbC, when compared with non-reinforced alloy.