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

• The effect of reaction temperature on formation of Al3Ti particles was studied.
• The effect of Al3Ti particles on grain refinement of α-Al matrix was discussed.
• The strengthening mechanism of in-situ Al3Ti/Al composites was studied.

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 °C and 785 °C) after ultrasonic vibration for 15 min. When the temperature was increased to 835 °C, all Ti additions reacted with the Al melt to form fine Al3Ti particles which are evenly distributed in the α-Al matrix. As the temperature increasing, the average grain size of α-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 °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 in-situ formed Al3Ti particles on grain refinement of the α-Al matrix was presented. The strengthening mechanism of the in-situ Al3Ti/Al composites was also discussed.

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