A novel approach hybridizing lithography-pressureless sintering additive manufacturing to go beyond the critical casting size limit of Fe-based bulk metallic glass

Fe-based bulk metallic glasses (BMGs) have high potential to be applied in biomedical devices, automotive and aerospace, and sports equipment due to their exceptional mechanical, physical and chemical properties. However, they have low glass forming ability (GFA) and high tendency to crack during solidification, restricting its critical casting size to a few millimeters which represents the bottleneck for broader industrial-scale utilization. Metal Additive Manufacturing (MAM) is a promising strategy to fabricate BMGs with larger sizes and complex geometries, bypassing the current bottleneck. Nevertheless, the fusion-based-AM techniques such as selective laser melting (SLM) trigger crystallization of the amorphous structure due to high thermal input. Sinter-based MAM is another strategy that decouples shaping and consolidation, preventing cracking and ability to process difficult-to-print materials. Lithography MAM (LMAM) offers exceptional surface quality, dimensional accuracy, and ability to process fine powders. Hence, this research proposes a novel approach hybridizing LMAM and pressure-less sintering approach to fabricate high-precision, complex, and dense monolithic Fe-based bulk metallic glass (BMG) components, achieving maximum amorphous content and exceeding the critical casting thickness limitations. The sample achieved a relative density of 65.934% with high amorphous content (87.45%) at 800 °C for 180 min. While the sample sintered at 660 °C with high heating rate (30 °C/min) for 120 min achieved relative density 65.456% and 90.60% amorphous content. SEM examination confirmed inter-particles diffusion, resulting in a modulus of rupture (MOR) of 4.1–7.9 MPa. These findings highlight the potential of utilizing LMAM to overcome the limited critical casting thickness of Fe-based BMG and maintain the high amorphous content.