Study On Processing Condition Of B₄C/Al Composites Prepared By Stirring Casting

Aluminum-based composites is one of the most important metal matrix composites widely used due to its' good comprehensive performance. But it was very limited in application of some special field such as inertia system or parts of the guided missile, because the strength, ductility or the wear resistance are not so satisfactory in some plain Al-based composites.The aim of this work is to prepare a new type of Al-based composites, including the selection of the matrix and reinforced-particles and the preparing technique, which is based on the processing of the previous composites SiCp/Al prepared by Beijing Institute of Aeronautical Materials. The new composites to be prepared should have better strength, toughness and wear resistance than the previous one so as to expand the application rage and industry development.Following the choice of the materials, taking ZL205A alloy as the matrix and boron carbide as the reinforcement, the experiment was carried out in air by the stir-furnace. After testing under the different preparing condition, a way has been found suitable for making the new composites, that is, pre-oxidizing and warming-up to the boron carbide, than gradually adding it into the glutinous molten aluminum obtained by regulating the temperature and stirring velocity. Meantime, SiCp/Al and Al2O3P/Al composites were also prepared in the same way for comparative investigation.The results of performance testing indicated that B4CpCp/Al composites has a higher strength, toughness and a lower wear resistance than the both of SiCp/Al and Al2O3P/AI composites, and even has a remarkable increase in ductility and elastic modulus compared to the previous composites SiCp/Al.Analyzing to the interface condition shows that the combination of B4C/Al interface is better than those of SiC/Al and Al2O3/Al. In certain temperature, reaction occurred in the interface between boron carbide and aluminum. The production was mainly a little Al3BC so that it has less effect on the composites. Mechanism of the interface reaction is dissolution-deposition.