Role of trace nanoparticles in establishing fully optimized microstructure configuration of cold-rolled Al alloy

Abstract

In this paper, we took cold-rolled Al-Cu5.0-Mg0.5-Si0.5 alloy as the research object. The roles of 0.1 wt% in-situ nano-TiC and nano-TiC-TiB2 in solid–liquid and solid-state transformations (solution plus aging precipitation) were systematically investigated and compared. We found that trace in-situ nanoparticles can stimulate the nucleation of α-Al dendrites and hinder their growth, meanwhile serving as the heat storage and heat sustained-release carriers during solid–liquid transformation. In the process of solid-state transformation, recrystallization nucleation is promoted, and grain boundaries are pinned by nanoparticles. Meanwhile, the nucleation of Al2Cu is accelerated, and refined Al2Cu distributes more uniformly. Besides, similarities and differences in the manipulation mechanisms of nano-TiC and nano-TiC-TiB2 during solid–liquid and solid-state transformations were analyzed. The mechanical properties and the responsible strengthening mechanisms were discussed in detail.

Keywords

• In-situ nanoparticles
• Solid–liquid transformation
• Solid-state transformation
• Microstructure configuration