Comprehensive Analysis of Microstructure and Hot Deformation Behavior of Al-Cu-Y-Mg-Cr-Zr-Ti-Fe-Si Alloy

Low sensitivity to hot cracking is very important not only for casting but also for ingots of wrought alloys. Doping of Al-Cu-(Mg) alloys by eutectic forming elements provides an increasing resistance to hot cracking susceptibility, but it also leads to a decrease in plasticity. The quasi-binary alloys based on an Al-Cu-REM system with an atomic ratio of Cu/REM = 4 have a high solidus temperature, narrow solidification range and fine microstructure. The detailed investigation of microstructure, precipitation and hot deformation behavior, and mechanical properties of novel Al-Cu-Y-Mg-Cr-Zr-Ti-Fe-Si alloy was performed in this study. The fine Al8Cu4Y, needle-shaped Al11Cu2Y2Si2, compact primary (Al,Ti)84Cu6.4Y4.3Cr5.3 and Q (Al8Cu2Mg8Si6) phases were identified in the as-cast microstructure. Near-spherical coarse Al3(Zr,Y) and fine Al45Cr7 precipitates with a size of 60 nm and 10 nm were formed after 3 h of solution treatment at 580 degrees C. S '(Al2CuMg) precipitates with an average diameter of 140 nm, thickness of 6 nm and calculated volume fraction of 0.033 strengthened 36 HV during aging at 210 degrees C for 3 h. Three-dimensional hot processing maps demonstrated an excellent and stable deformation behavior at 440-540 degrees C and strain rates of 0.01-10 s-1. The rolled sheets had a good combination of yield strength (313 MPa) and plasticity (10.8%) in the recrystallized at 580 degrees C, with water quenched and aged at 210 degrees C for a 3 h state. The main calculated effect in the yield strength was contributed by Al45Cr7 precipitates.

Automated summary

Low sensitivity to hot cracking is crucial for both casting and ingots of wrought alloys. The study investigated the microstructure, precipitation, hot deformation behavior, and mechanical properties of a novel Al-Cu-Y-Mg-Cr-Zr-Ti-Fe-Si alloy. The alloy exhibited high solidus temperature, narrow solidification range, and fine microstructure. The addition of eutectic forming elements improved resistance to hot cracking but decreased plasticity. The alloy showed good deformation behavior and mechanical properties after aging treatment.