Effect of TiC nano-addition on microstructure and properties of 7075 aluminum alloy fabricated by laser-arc wire additive manufacturing

Abstract

7075 aluminum alloy fabricated by laser-arc wire additive manufacturing suffers from coarse grains, severe porosity, hot cracking, and poor mechanical performance. Herein, 1.0 wt.% TiC nanoparticles were employed to modify the alloy for microstructure and performance optimization. Experimental findings reveal TiC particulates act as heterogeneous nucleation substrates. They effectively reduce the mean grain dimension from 111.8 μm down to 12.5 μm, while altering bulky columnar crystals into evenly distributed equiaxed grains. Introducing TiC nanoparticles significantly eliminates solidification defects. Severe internal defects make unmodified 7075 samples untestable for tensile measurement, while TiC-modified samples achieve a high as-deposited tensile strength of 292 MPa, with distinct mechanical properties in different deposition directions. Combined strengthening mechanisms including grain refinement, particle dispersion and solid solution hardening jointly optimize the microstructural characteristics, and enhances mechanical properties by hindering dislocation motion and stabilizing grain boundaries. This work provides a reliable technical reference for high-quality laser-arc hybrid additive manufacturing of high-strength 7075 aluminum alloys