Comparative investigation of microstructure, mechanical properties and strengthening mechanisms of Al-12Si/TiB2 fabricated by selective laser melting and hot pressing

• Published in: Ceramics international Vol. 44; no. 15; pp. 17635 - 17642
• Main Authors: Xi, L.X., Zhang, H., Wang, P., Li, H.C., Prashanth, K.G., Lin, K.J., Kaban, I., Gu, D.D.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15-10-2018
• Subjects: Al-12Si/TiB2; Hot pressing; Microstructure and mechanical properties; Selective laser melting; Strengthening mechanisms; Wetting behavior; Al-12Si/TiB2; Hot pressing; Wetting behavior; Selective laser melting; Strengthening mechanisms; Microstructure and mechanical properties
• ISSN: 0272-8842; 1873-3956
• DOI: 10.1016/j.ceramint.2018.06.225

Near-fully dense Al-12Si matrix composites reinforced with TiB2 ceramic particles (2 wt%) were successfully fabricated by selective laser melting (SLM) and hot pressing (HP) of powder mixtures. TiB2 ceramic particles are homogeneously distributed in the Al-12Si matrix at the micrometer-scale owing to a very good wetting between molten Al-12Si alloy and TiB2 ceramic. The microstructural analysis of the as-fabricated SLM samples show the formation of a supersaturated α-Al phase and the decrease of free residual Si with respect to the hot-pressed ones. Both composites exhibit a fine microstructure with a grain size of ~ 5.1 µm and ~ 5.8 µm for SLM- and HP-fabricated samples with addition of TiB2 ceramic particles. The SLM Al-12Si/TiB2 composite exhibits significantly improved microhardness (~ 142 ± 6.0 HV0.05) and yield strength (~247 ± 4.0 MPa) compared to the corresponding HP one. Fine cell morphology and nanostructured dispersion strengthening are responsible for the improved mechanical strength of the Al-12Si/TiB2 composite processed by SLM.