Selective Laser Melting of Mechanically Alloyed Metastable Al5Fe2 Powders

Abstract

Aluminum alloys, which are high-strength lightweight materials, were processed by selective laser melting (SLM) with high-energy consumption and poor finish due to quick heat dissipation. Previous investigations reported that SLM with 300 W laser power and 500 mm/s scanning speed can process the aluminum alloys, such as Al-Si12 and AlSi10Mg. This work aims to process the powders to alter their properties and to reduce the laser intensity required in the process, and it also reports that the SLM-processed Al–Fe alloys utilize the metastable alloy by mechanical alloying (MA). The elemental Al and Fe powders were first alloyed in a ball mill in a relative short time period (∼15 h) employing high milling intensities, high ball-to-powder ratio (≥20:1), and high milling velocities (≥400 rpm), which produced fine metastable Al–Fe powders, and these powders were processed later by the SLM. The optimum laser power, the scanning speed, hatch distance, and substrate temperature were investigated by a series of experiments. Experimental results indicated that decreasing the laser energy density while increasing the laser scanning speed can benefit for smoother laser hatch lines, and the metastable Al5Fe2 alloy powders can be processed and stabilized under a 200-W laser energy density and a scanning speed of 1000 mm/s. It is expected that the combination of pre-excited materials in a metastable phase will open a new window to optimize the SLM process for aluminum alloys and other metallic alloys.