Young’s Modulus, Damping, and Thermal Expansion of a Sustainable Magnesium Composite Containing Recycled C-Fibers

Carbon fiber-reinforced magnesium (CFRM) composites are promising materials for aerospace, automotive, and structural applications due to their high specific strength, modulus, and low coefficient of thermal expansion (CTE). These composites combine the lightweight, high damping capacity, and corrosion-resistant properties of magnesium alloys with the strength and stiffness of carbon fibers, improving both mechanical and thermal performance. This study investigates the thermal expansion, dynamic Young’s modulus, and damping of CFRM composites fabricated by adding recycled carbon fibers (rCF) to molten AZ91 magnesium alloy using stir casting. The molten mixture was stirred for uniform fiber distribution and then solidified and hot-extruded to form the final profile. The effects of varying rCF content (2.5 and 5 wt.%) on the composite’s thermal and mechanical properties were analyzed. The results showed that increasing rCF content significantly reduced the CTE, indicating improved thermal stability. Additionally, dynamic Young’s modulus increased with higher rCF content, emphasizing the importance of carbon fiber in enhancing the material’s stiffness. The use of rCF provides an environmentally more sustainable and cost-effective alternative to virgin CF while maintaining high performance. These findings support the development of CFRM composites for lightweight, high-strength applications with improved dimensional stability, using rCF as reinforcement.