記事 Corrosion of Magnesium and Magnesium Alloys 3 min read • July, 2001 • 材料特性 › 耐食性と耐環境性 • 最終技術レビュー：2026 Abstract This comprehensive analysis examines the corrosion behavior of magnesium and its alloys, focusing on the crucial factors affecting their degradation in various environments. The study explores the impact of chemical composition, environmental conditions, and surface treatments on corrosion resistance. Special attention is given to the effects of heavy-metal impurities, atmospheric conditions, and chemical environments. Introduction The corrosion resistance of magnesium and magnesium parts is influenced by factors similar to other metals, though their electrochemical activity significantly magnifies these effects. While unalloyed magnesium sees limited structural use, the corrosion resistance of magnesium alloys remains a primary concern for designers and engineers. Major Magnesium Alloy Systems Aluminum-Containing Alloys These alloys contain 2-10% aluminum with minor zinc and manganese additions. They offer: Wide availability at moderate costs Good mechanical properties up to 95-120°C Rapid property deterioration above these temperatures Zirconium-Based Alloys These alloys combine various elements (rare earth, zinc, thorium, silver) with zirconium, offering: Improved mechanical properties through fine grain structure Superior elevated temperature performance Higher costs due to specialized manufacturing requirements Chemical Composition and Corrosion Effects Element Categories and Their Impact Six elements (aluminum, manganese, sodium, silicon, tin, and lead) plus thorium, zirconium, beryllium, cerium, praseodymium, and yttrium show minimal effect on saltwater corrosion when present up to 5% or their solubility limits.Four elements (cadmium, zinc, calcium, and silver) demonstrate mild-to-moderate accelerating effects on corrosion rates. Iron, nickel, copper, and cobalt show extremely deleterious effects due to their: Low solid solubility limits Activity as cathodic sites Water reduction capabilities at magnesium's expense 材料の耐食性および耐環境性を評価する 腐食、化学物質への曝露、温度、および環境性能に関する参照データを用いて、材料を比較する。 材料特性の比較 ガイド付きツアーに参加する › Tolerance Limits and Interactions The iron tolerance in magnesium-aluminum alloys depends on manganese content. For AZ91 with 0.15% manganese, iron tolerance is 0.0048% (0.032 x 0.15%). Nickel tolerance varies with cast form and grain size, with low-pressure cast alloys showing 10-ppm tolerance in F temper. Heat Treatment and Processing Effects Studies using controlled purity AZ91 alloy in both pressure forms have established: F temper (as cast) T4 temper (16h at 410°C and quenched) T6 temper (16h at 410°C, quenched, aged 4h at 215°C) High-iron AZ91C showed consistently poor corrosion performance, while high-purity alloys with T5 and T6 tempers achieved corrosion rates under 0.25 mm/yr. Environmental Factors Atmospheric Effects Clean, unprotected surfaces develop protective gray films in salt-free atmospheres. Corrosion resistance varies with humidity: 9.5% humidity: No corrosion after 18 months 30% humidity: Minor corrosion 80% humidity: Considerable corrosion Water and Solution Effects Fresh Water: Forms protective films in stagnant conditions Salt Solutions: Severity depends on metal content and chloride presence Acids and Alkalis: Rapid attack except by HF and H2CrO4 Organic Compounds: Generally non-corrosive except for anhydrous methanol Gases: Minimal corrosion from dry halogens; increased attack with water presence