Porous Mg–Mn Alloys Fabricated by Powder Metallurgy: Microstructural Evolution and Structure–Property Relationships
摘要
Porous magnesium alloys exhibit great potential for lightweight structural and biomedical applications by combining the intrinsic lightness and biodegradability of magnesium with the high specific strength and energy absorption capacity of porous structures. This study systematically investigates the effects of sintering temperature (540 °C to 600 °C) and manganese content (1.0 to 2.5 wt pct) on the microstructure and mechanical as well as corrosion properties of porous Mg–Mn alloys fabricated via powder metallurgy. Increasing the sintering temperature enhances atomic diffusion and promotes the formation and growth of sintering necks, thereby reducing porosity from 36.19 to 31.93 pct. The optimal compressive strength of 17.5 MPa was achieved at 580 °C. The addition of Mn further refines the grain structure and homogenizes pore distribution. Compressive strength increases with Mn content, reaching a maximum of 19.7 MPa in the alloy with 2.5 wt pct Mn, albeit accompanied by a more brittle failure mode. Electrochemical and immersion tests demonstrate that an appropriate Mn content (≤ 2.0 wt pct) significantly improves corrosion resistance, achieving a minimum corrosion current density of 4.1051 × 10−4 A·cm−2, primarily due to reduced porosity impeding the penetration of corrosive media. However, excessive Mn (2.5 wt pct) undermines this improvement by promoting the formation of cathodic secondary phases, which accelerate corrosion through micro-galvanic coupling. This work provides both a practical processing guideline and a theoretical basis for the development of high-performance porous magnesium alloys.