Static coarsening behaviour of lamellar microstructure in selective laser melted Ti-6Al-4V

Static coarsening mechanism of selective laser melted (SLMed) Ti-6Al-4V with a lamellar microstructure was established at temperatures from 700 degrees C to 950 degrees C. Microstructure evolution revealed that high heat treatment temperature facilitated martensite decomposition and promoted lamellae growth. At each temperature, the growth rate decreased with increasing holding time. The static coarsening behaviour of SLMed Ti-6Al-4V can be interpreted by Lifshitz, Slyozov, and Wagner (LSW) theory. The coarsening coefficient were 0.33, 0.33-0.4, 0.4-0.5 for 700-800 degrees C, 900 degrees C and 950 degrees C, respectively. This indicated the coarsening mechanism was bulk diffusion at 700-800 degrees C, and a combination of bulk diffusion and interface reaction at 900 degrees C and 950 degrees C conditions. (C) 2019 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.