In Situ Synthesis Of Al₃Ti Particulate-Reinforced Aluminum Matrix Composites

Al₃Ti/Al composites were in situ fabricated by preheating Al and Ti powder blocks at some temperatures. The reaction process of Ti-(x+3)Al(x>0)system, the microscopic morphology and microstnicture of the products were studied by using DSC,XRD,SEM etc. The reaction mechanism of Ti-(x+3)Al(x>0)system was analyzed through thermodynamics calculation and the established kinetic model. The hardness and wear property of the composites were tested. The influencing factors on the morphology, density and hardness of Al₃Ti/Al composites were also discussed.The experimental results showed that the explosion reaction of 3 Al+Tis→Al₃Ti was induced by the melted aluminum and the peritectic reaction. The Al₃Ti/Al composites were fabricated because of superfluous aluminum. Ingredients, the preheated temperature and the granularity of Ti were found to have obvious influences on morphology and density of the products. With the increase of the content of aluminum, the preheating temperature and adiabatic temperature of the system were depressed. Thus the melting volume of Al₃Ti was decreased or no-melting, and the diameter of Al₃Ti becomes small with the increased density of the composites. As the preheating temperature increases, the velocity of the reaction rises, Al₃Tl particles grow up with anomalous morphology. As the granularity of Ti particles reduces, the reaction becomes less vigorous.The results of property evaluation of Al₃Ti/Al composites show that the hardness is enhanced with the increase of Al₃Ti particle. Although the volume fraction of Al₃TC is larger, the wear resistance of Al₃Ti-2Al and Al₃Ti-4Al composites don't enhance obviously because of the poor density. Al₃Ti-6Al composites represent much higher wear resistance compared with aluminum, when the load is 50N,100N,150N, its wear resistance is .respectively, 3,2.1,3.5 6 times of aluminum, and 1.4 times of A356 alloy under the 150N load. Abrasive and adhesive wear is dominant mechanism during the dry sliding wear with slight oxidation wear.