Infiltration of Light Metals into Stainless Steel Preforms Fabricated by Indirect Selective Laser Sintering

In this study, we attempted to infiltrate molten aluminum, magnesium, and magnesium-zinc alloy into stainless steel preforms fabricated by indirect selective laser sintering (SLS). In the case of aluminum, infiltration did not occur; it was inhibited by the intermetallic compound (Al3Fe) formed by the active reaction between molten aluminum and stainless steel powder. Molten magnesium and magnesium-zinc alloy, however, smoothly infiltrated into the stainless steel preforms, and the infiltrated parts were found to maintain excellent dimensional accuracy. The hardness and tensile strength of the infiltrated parts of magnesium are 65 HRB and 265 MPa, respectively, and the corresponding values for magnesium-zinc alloy are 72 HRB and 305 MPa, respectively. The tensile strengths of the infiltrated parts are significantly higher than those of the casting materials (106 MPa for magnesium and 270 MPa for magnesium-zinc alloy). We believe that the large increase in tensile strength after infiltration was due to the composite reinforcement of the matrix and stainless steel particles. Thus, the infiltration of magnesium and magnesium-zinc alloy into stainless steel powder preform can be considered as an effective indirect SLS technique for producing lightweight infiltrated metal-alloy parts.