The Portevin-Le Chatelier (PLC) effect in an Al-Cu aluminum alloy fabricated by selective laser melting

An Al-Cu alloy fabricated by selective laser melting (SLM) was chosen in this study for the investigation of Portevin-Le Chatelier (PLC) effects. The effects of the process parameters, the building orientation, and the heat treatment were studied to reveal the correlation between the microstructure and the plastic instability. Serrated flow can be observed in all the as-built specimens due to the high concentration of the solute atoms and high dislocation density generated by the high cooling rate during the process. Strong anisotropy in PLC effects has been observed in the as-built samples, which is attributed to the grain structure and the texture. PLC effects changes a lot after the heat treatments. The solution treatment decreases the dislocation density. Hence, the PLC effects disappear. 0" nucleated at 446 K can delay the onset of the PLC effects. When aged at 466 K, with the absence of 0", the onset strain of the PLC effect with the same duration is lower. As the aging duration increases from 1 h to 6 h, PLC effects become weaker and finally disappear. The concentration of the solute atom and the dislocation density decrease as the aging duration increases. Both aspects are responsible for the attenuation of PLC effects.