Jiao Lei

Microstructures of in-situ TiB2/7055Al Composites by the Ultrasonic and Magnetic Coupled Field

Abstract The TiB 2 /7055Al Nano-composites were fabricated under the ultrasonic and magnetic coupled field. The results show that TiB 2 particles in the coupled field have a small size, with 80∼100 nm, a ball shape, a uniform distribution and a reaction to generate TiB 2 particles with high efficiency. When the ultrasonic power is 0.8 kW and exciting current of magnetic field is 200 A, frequency is 5 Hz, approximately 82.4% of TiB 2 reinforcement particles sizes are in range of 0.2∼0.5 μm, the number of particles whose sizes are in the range of 0.8∼1.2 μm reduce to about 1.6%, therefore, the thinning effect is nearly twice as much as generated in a single ultrasonic field of 0.8 kW.

High Strain Rate Superplasticity of in situ Al 3 Zr/6063Al Composites

Abstract In situ 5wt%Al 3 Zr/6063Al composites were fabricate by a direct melt reaction method (DMR) and then processed by deformation pretreatment. Process of the pretreatment was forging of 70% deformation at 450 °C and friction stir processing (FSP). The high strain rate superplasticity of the composites was studied by modern analytic determination methods. The results show that the average grain size of the composites is less than 10 μm after forging and FSP. The composites exhibit superplasticity at the temperature from 350 to 500 °C and initial strain rate from 1.0×10 −3 s −1 to 1.0×10 −1 s −1 . The elongation reaches 330% and the sensitive index ( m value) is 0.45 at the initial strain rate of 1.0×10 −2 s −1 and the temperature of 500 °C. The dominant mechanisms of superplastic deformation are grain boundary sliding and dislocation slip which is synergized with moderate grain growth and dynamic continuous recrystallization