Magnesium Alloy vs Aluminum Alloy

Is Magnesium Alloy Suitable for Powered Mobility and Human-Powered Gear?

Summary: Magnesium alloy is the optimal lightweight solution for powered mobility and human-powered gear, reducing weight by 33% compared to aluminum alloy. This article details its application scenarios, engineering requirements, trade-offs with aluminum alloy, common mistakes, and supply chain support to help you make informed material choices.

Key Takeaways

Core Advantage: Magnesium alloy is the best lightweight solution for improving the "power-to-weight ratio" of powered mobility equipment, reducing weight by 33% compared to 6061 aluminum alloy, balancing light weight and controllability.

Major Risks: Fatigue fracture under high-frequency dynamic alternating loads (fatigue limit is 60%-70% of aluminum alloy); galvanic corrosion without isolation (magnesium is prone to anodic dissolution when in contact with steel and copper).

Not Recommended Scenarios: ① Transmission core components with continuous working temperature ≥120°C (prone to creep and strength reduction); ② Unprotected water-exposed load-bearing structures without anti-corrosion treatment.

Recommended Strategy: Prioritize application in non-load-bearing structures, motor housings, and optimization of vehicle unsprung mass (1kg reduction in unsprung mass is equivalent to 5-10kg reduction in sprung mass).

The Verdict (Engineering Conclusion)

Magnesium alloy is an inevitable upgrade from aluminum alloy for manned/human-assisted power equipment (electric scooters, E-bikes, hand-held tools, etc.). It is widely used in magnesium alloy for E-bike and magnesium alloy for electric scooter due to its unique advantages:

•          Lightweight: Reduces operational fatigue, improves work efficiency and battery life of hand-held equipment;

•          Shock Absorption: Its damping coefficient is more than 10 times that of aluminum alloy, absorbing high-frequency vibrations, reducing noise, and enhancing handling feel.

Prerequisites for Replacement (Must Meet):

•          Stress Optimization: Increase local wall thickness and arrange reinforcing ribs to compensate for the insufficient rigidity of magnesium alloy (45GPa), which is only 64% of aluminum alloy (70GPa);

•          Fastener Treatment: Direct tapping on magnesium matrix is strictly prohibited; H6 tolerance steel thread bushings + anti-loosening structures must be pre-embedded.

Quick Verdict (Engineering Quick Judgment)

Recommended Scenarios

•          Personal Vehicles: E-bike motor cooling housings, electric scooter folding columns, light balance wheel hubs (magnesium alloy for E-bike motor housing is highly recommended);

•          Hand-Held Power Equipment: Chainsaw bodies, garden trimmer frames, portable impact drill housings (weight reduction directly improves work efficiency, i.e., "weight reduction = production increase");

•          Mobile Robots: Delivery robot chassis brackets and protective armor (lightweight improves battery life, shock absorption protects internal precision components).

 Conditional Requirements

•          Surface Anti-Corrosion: MAO (Micro-Arc Oxidation, an anti-corrosion process for magnesium alloy) + powder coating composite process (MAO layer 15-25μm, powder layer ≥60μm), passing 72-hour neutral salt spray test (GB/T 10125-2021);

•          Material Selection: ZK60 magnesium alloy (tensile strength ≥380MPa, yield strength ≥300MPa) for high dynamic impact parts; AZ91D semi-solid die casting (0.5mm ultra-thin wall) for complex thin-walled parts (ZK60 magnesium alloy application is ideal for high-impact scenarios).

 Not Recommended Scenarios

•          Internal Combustion Engine Direct Connection Parts: Areas with long-term working temperature ≥150°C (prone to creep and deformation failure);

•          Extreme Impact Points: Unreinforced bottom guard plates and bumpers (high notch sensitivity, prone to brittle fracture).