Effect of reaction temperature on the microstructures and mechanical properties of high-intensity ultrasonic assisted in-situ Al3Ti/2024 Al composites

Al3Ti/2024 Al composites were fabricated by high-intensity ultrasonic assisted in-situ casting method. The effect of reaction temperature on microstructures and mechanical properties of the in-situ composites was studied. The results show that the reaction between Ti particles and Al melt was incomplete at low temperatures (e. g. 735 degrees C and 785 degrees C) after ultrasonic vibration for 15 min. When the temperature was increased to 835 degrees C, all Ti additions reacted with the Al melt to form fine Al3Ti particles which are evenly distributed in the alpha-Al matrix. As the temperature increasing, the average grain size of alpha-Al matrix decreased, while the yield strength was improved significantly. The ultimate tensile strength and yield strength of the composite which was fabricated at 835 degrees C were 446 MPa and 357 MPa, respectively, which are increased by 30% compared with those of the composite without ultrasonic treatment. Moreover, the effect of ultrasonic vibration on formation of Al3Ti particles was studied. The effect of insitu formed Al3Ti particles on grain refinement of the alpha-Al matrix was presented. The strengthening mechanism of the in-situ Al3Ti/Al composites was also discussed. (C) 2016 Elsevier B.V. All rights reserved.