Bio-Inspired Functional Surface Fabricated by Electrically Assisted Micro-Embossing of AZ31 Magnesium Alloy

Area of Science:

• Materials Science
• Surface Engineering
• Manufacturing Processes

Background:

• Bio-inspired functional surfaces are critical for automotive and aeronautics industries.
• Micro-embossing is a scalable method for creating these surfaces but suffers from size effects like defects and die breakage.
• Electrically assisted micro-forming offers a solution by reducing size effects and improving material formability.

Purpose of the Study:

• To investigate the efficacy of electrically assisted micro-forming for fabricating bio-inspired textures on metallic surfaces.
• To determine optimal current densities for micro-embossing using bulk metallic glass dies.
• To analyze the impact of current density on micro-channel filling quality and die integrity.

Main Methods:

• Utilized thermoplastic forming with photolithographic silicon molds to create textured bulk metallic glass dies.
• Embossed micro-channels (7 μm) and sharklet patterns (10 μm) on magnesium alloy using varying current densities.
• Controlled processing temperature to remain below the glass transition temperature of the dies.

Main Results:

• Successful fabrication of large-area bio-inspired textures on magnesium alloy was achieved at current densities exceeding a 6 A/mm² threshold.
• Optimal surface quality was observed at a current density of 13 A/mm².
• Increased current densities led to a nonlinear rise in filling depth and depth-width ratio, with temperature control being critical.

Conclusions:

• Electrically assisted micro-forming is a viable hybrid process for overcoming limitations in traditional micro-embossing.
• Current density is a key parameter for controlling micro-feature formation and surface quality in bio-inspired metallic surfaces.
• Maintaining die temperature below the glass transition point is essential for preventing die failure and ensuring process reliability.