ZrC+TiC synergically reinforced metal matrix composites with micro/nanoscale reinforcements prepared by laser powder bed fusion
Lixia Xi, Lili Feng, Dongdong Gu, Ruiqi Wang, Baran Sarac, Konda Gokuldoss Prashanth, J. Eckert
Abstract
The addition of hybrid ceramic reinforcing phases provides the possibility of regulating the in-situ reaction and effective strengthening in laser additive manufactured aluminum matrix composites (AMCs). In this work, AMCs reinforced with (ZrC + TiC) solid solution ceramics with micro/nanoscale microstructural features are fabricated by laser powder bed fusion (LPBF). The influence of laser power on the manufacturing quality, the microhardness and the wear properties of the LPBF-fabricated (ZrC + TiC)/Al composites is investigated. Moreover, the reaction mechanism between the ZrC and TiC ceramics in the LPBF process is revealed. The tensile properties of the (ZrC + TiC)/Al composites with different (ZrC + TiC) contents prepared at optimal process parameters are compared. During the LPBF process, the ZrC and TiC ceramics are incompletely melted. On the ceramic particles, a thin (Ti,Zr)C layer formed and large amounts of (Ti,Zr)C nanoparticles precipitated via a dissolution-precipitation mechanism. When the laser power increases from 375 to 425 W, the manufacturing quality, microhardness, tensile and wear properties of the (ZrC + TiC)/Al composites increase. The tensile strength of 10 wt.% (ZrC + TiC)/Al composites prepared at optimal processing parameters reaches a high strength value of ∼227 MPa with a uniform elongation of ∼6.7%, which is three times higher than that of the unreinforced Al-matrix. This is ascribed to the combined effects of Orowan strengthening, coefficient of thermal expansion (CTE) mismatch strengthening, load-bearing strengthening and grain refinement strengthening.