Development and Characteristics of New Biobased Magnesium Composites

The integration of sustainable and natural waste-derived materials into lightweight metals presents a promising strategy with both environmental and performance-related benefits. In this study, a biobased magnesium composite reinforced with dried leaf powder (DLP) derived from fallen waste leaves was synthesized using a controlled powder metallurgy method incorporating energy efficient hybrid microwave sintering, followed by hot extrusion at varying temperatures (350 °C, 250 °C, 150 °C). Microstructural analysis revealed that the addition of DLP had minimal effect on the overall grain morphology, while lower extrusion temperatures promoted finer grains due to restricted grain growth. Mg–5DLP composites consistently exhibited higher porosity than pure Mg, primarily due to the evaporation of organic constituents during sintering. The damping performance of the biomass-containing materials was improved (54.5% increase), particularly at lower extrusion temperatures (250 °C), though mechanical performance showed a trade-off with reduced hardness and compressive strength. A slight increase in yield strength at lower extrusion temperatures was attributed to retained dislocation density and grain refinement. Thermal stability remained largely unaffected, while corrosion behavior was strongly dependent on both DLP addition and extrusion temperature, with Mg–5DLP samples corroding faster than pure Mg when extruded at higher temperatures; interestingly, however, at the lowest extrusion temperature (150 °C), improved corrosion resistance to pure Mg (1.3 mm/year for Mg-5DLP vs. 2.0 mm/year for pure Mg) was observed. Overall, this work demonstrates that extrusion temperature is a critical factor in controlling the microstructure, thermal response, damping response, mechanical behavior and corrosion of biobased composites. The study not only highlights the potential of using direct biomass reinforcement of magnesium to synthesize lightweight, ecofriendly materials, but also lays a strong foundation for future investigations into biobased composite design, processing optimization, and property tailoring.