Magnesium-Lithium Alloy Cold Workability via Aluminum Addition
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Solution Overview
Problem
Magnesium-lithium alloys with lithium content above 10.5% struggle to balance corrosion resistance and cold workability, and existing methods for producing these alloys often result in inadequate tensile strength and increased crystal grain size, limiting their practical application in lightweight structural materials for electronic devices.
Innovation Solution
A magnesium-lithium alloy with lithium content between 10.5% and 16.0%, aluminum content between 0.50% and 1.50%, and a specific processing method involving cold plastic working and annealing at controlled temperatures to achieve a single β phase with improved tensile strength and corrosion resistance, while maintaining cold workability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If lithium content is increased to improve cold workability, then cold workability is improved, but corrosion resistance deteriorates
Solution Approach 1:
The invention changes the chemical composition parameters by adding aluminum (0.5-1.5 mass%) to the magnesium-lithium alloy system. This parameter change modifies the electrochemical properties and phase structure, enabling the alloy to achieve both improved cold workability (through β phase formation) and maintained corrosion resistance (through aluminum's protective effect), thus resolving the contradiction between cold workability and corrosion resistance
Solution Approach 2:
The invention creates a composite alloy system by combining magnesium, lithium, and aluminum elements. The multi-element composition forms a complex phase structure (α-Mg + β-MgLi + Al-containing phases) that integrates the advantages of each element: Li provides cold workability, Mg provides base structure, and Al provides corrosion resistance, thereby resolving the contradiction between cold workability and corrosion resistance
2Ease of operation
If heat treatment temperature is increased to recrystallize the alloy, then press workability is improved, but crystal grain size increases excessively
Solution Approach 1:
The invention optimizes the heat treatment parameter by controlling the temperature range at 170-250°C. This specific parameter range is sufficient to activate recrystallization and improve press workability while preventing excessive grain growth that would occur at higher temperatures, thus resolving the contradiction between press workability and crystal grain size control
3Manufacturing precision
If cold rolling reduction is increased to improve rolled material quality, then rolled material quality is improved, but tensile strength decreases
Solution Approach 1:
The invention changes the compositional parameter by adding aluminum (0.5-1.5 mass%) to the alloy system. This compositional modification enables the material to withstand higher cold rolling reductions (30-60%) without excessive tensile strength loss, as aluminum strengthens the matrix and prevents premature failure during high-reduction processing, thus resolving the contradiction between rolled material quality and tensile strength retention
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The alloy achieves balanced corrosion resistance and cold workability, with tensile strength of at least 150 MPa and Vickers hardness of 50 or higher, suitable for lightweight structural applications in electronic devices, such as mobile phones and digital cameras, while maintaining low surface electrical resistivity.
Implementation Method 1
magnesium-lithium alloys, which contain lithium, take a mixed phase of the hcp structure and the bcc structure (β phase) at a lithium content of 6 to 10.5 mass %, and a single β phase at a lithium content of 10.5 mass % and higher
Implementation Method 2
heat-treating at 140 to 150° C. to recrystallize
Data Source
AI summary
The present invention provides a magnesium-lithium alloy having both corrosion resistance and cold workability balanced at high levels, a certain degree of tensile strength, and very light weight, as well as a rolled material and a formed article made of this alloy. The alloy of the invention contains not less than 10.5 mass % and not more than 16.0 mass % Li, not less than 0.50 mass % and not more than 1.50 mass % Al, and the balance of Mg, and has an average crystal grain size of not smaller than 5 μm and not larger than 40 μm, and a tensile strength of not lower than 150 MPa or a Vickers hardness (HV) of not lower than 50.