High-Temperature Creep Behavior of Selective Laser Melting Manufactured Al-Si-Fe-Mn-Ni Alloy

The development of high-temperature creep-resistant Al alloys is essential for manufacturing aerospace and transportation equipment. Conventional creep-resistant Al alloys have several limitations, including high costs, complex heat treatment processes, and challenging processing requirements. Selective laser melting (SLM) technology enables the fabrication of metal materials with ultrafine microstructures and high concentrations of strengthening phases due to its rapid cooling rates, substantial temperature gradients, and unique thermal cycling. This capability provides a promising path for the development of next-generation creep-resistant Al alloys. In this study, a novel Al-9Si-3Fe-2Mn-Ni (mass fraction, %) alloy using the SLM technique was developed. This Al- Si alloy was engineered by controlling the diffusion of slow-diffusing elements and intermetallic compounds (IMCs) that strengthen the material. The high-temperature creep behavior of this alloy was evaluated through uniaxial tensile creep experiments conducted at varying deformation temperatures (300-400 o C) and applied stresses (33-132 MPa). The experimental results demonstrate that the alloy exhibits good creep performance under the experimental conditions. The stress exponent ranged from 6.4 to 13.6, showing a decreasing trend with increasing temperature. The creep deformation mechanism is known as dislocation creep. Below 350 (o) C, the continuous Al- Si eutectic network reduces the overall stress via load transfer, with IMCs strengthening the alloy via the Orowan mechanism. At 400 C-o , the Al- Si eutectic structure fractures and dissolves, with the IMCs and dispersed Si phases providing the primary strengthening mechanism. Increased applied stress amplifies the dislocation slip systems within the alloy, intensifying the interactions between dislocations and precipitates, leading to destabilization and deformation and ultimately reducing creep life.