Fabrication of aluminum (AlSi10Mg) matrix particle (Ti and Zr) reinforced composite foam using directed energy deposition

•This study investigates fabrication of particle reinforced composite foam (PRCF) using AlSi10Mg and foaming agents (TiH2 and ZrH2).•Decomposition of TiH2 and ZrH2 can not only form large pores, but also microscopic Kirkendall voids.•Many intermetallic compounds formed by reaction of aluminum and foaming agent are observed.•Improved wear resistance of PRCF is attributed to high modulus of elasticity and hardness of residual particles.•Oxide film generated during the foaming caused interlayer defects. This study fabricated aluminum (AlSi10Mg) foam using a directed energy deposition (DED) process. The foaming properties and microstructures are comparatively analyzed for different foaming agents (TiH2 and ZrH2). The foaming agent forms pores inside the deposition material and reacts with aluminum powder to produce an intermetallic compound. These compounds exhibit different shapes based on the type of foaming agent: Al3Ti particles are more spherical in shape than Al3Zr particles, which suppresses the formation of defects by reducing the stress around the particles. Consequently, considerably fewer defects are observed in the deposited region of the deposited foam AlSi10Mg (TiH2). Further, the oxide film thickness increases when high content ZrH2 is used; this causes defects at the interlayer and the interface. The results indicate that a porous metal with a maximum porosity of 20.61% can be fabricated with a laser output of 1100 W from the deposited foam AlSi10Mg (TiH2); further, a porous metal with a maximum porosity of 28.73% can be fabricated from the AlSi10Mg (ZrH2) specimen. The formation of oxides caused by the metal elements in the alloys during deposition contributes to foam stabilization. Thus, the porosity and pore size are higher than that for the deposited foam AlSi10Mg (TiH2) because a relatively large number of oxides stabilize the growth of pores. Meanwhile, Ti and Zr particles inside the deposited region show high hardness because they are embrittled by hydrogen, nitrogen, and oxygen. Therefore, the hardness of the deposited foam AlSi10Mg does not decrease despite the existence of pores.