Investigation of production and properties of aluminium based in?situ composites reinforced with boride

During cooling of aluminium?boron (Al?B) alloys two different boride phases come out. These are AlB12 and AlB2 phases. AlB12 transforms into AlB2 at about 1000 °C by a peritectic reaction. AlB2 is a stable phase at room temperature and lower temperatures. Due to formation of AlB2 in?situ within liquid alloy and being stable at room temperature have promoted a few past studies to use of this hard and wear resistant phase in production of new AlB2/Al type metal matrix composites.Throughout this study, instead of using expensive KBF4 (fluoride) salts, using boron containing minerals, which are cheap and ample in Turkey, Al/AlB2 composites have been produced via different casting methods. It is aimed investigating the structural properties such as aspect ratio and distribution of the in?situ formed AlB2 reinforcing phase by directly introducing boron containing minerals into different aluminium alloys. Finally, in this study, the effects of increasing the AlB2 reinforcing ratio, via gravity casting, centrifugal casting and squeeze casting methods, on the mechanical properties of the composites have been investigated.Gravity casting, centrifugial casting, squeeze casting, optical microscope, image analysis, SEM, XRD and wet chemical analysis techniques, hardness, tensile and compression tests were used. Results showed that, depending on the increase in the reinforcement phase, up to 300 % increase in the strength and hardness of the composite has been achieved.