Microstructures and Properties of V-Modified A380 Aluminum Alloy Produced by High Pressure Rheo-Squeeze Casting with Compound Field Treatment

The melt of V-modified A380 alloy aluminum alloy was treated by compound field of ultrasonic vibration (UV) and electromagnetic stirring (ES) around liquidus temperatures. Then the high pressure rheo-squeeze casting (HPRSC) process was used to produce an ingot with the alloy melt obtained. The results indicate that the polygonal Si₂V phase is precipitated after adding vanadium to the alloy. With the increasing of V content from 0 to 1.05%, the average length and volume fraction of β-Al₅FeSi phase is decreased to 30 μm and 1.44%, respectively. The refinement effects of UV, ES, and UV-ES compound field on the microstructure of the gravity casting alloy are as follows: UV-ES > UV > ES. When the pressure is increased from 0 to 400 MPa, the size of primary α-Al is decreased gradually, the morphology of β-Al₅FeSi phase is changed from an acicular to a fine fibrous-like one, and the polygonal Si₂V phase is refined to fine particle with an average grain diameter of about 8 μm. The ultimate tensile strength (UTS), yield strength (YS), and elongation of the alloy without V are lower than that of the alloy with 0.7% V under the same pressure. When the pressure is 400 MPa, the UTS, YS, and elongation of T6 heat-treated HPRSC alloy with 0.7% V are 301 MPa, 182 MPa, and 3.3%, respectively. With the decrease in the length of β-Al₅FeSi phase, the quality index of the HPRSC alloy is increased.