Dealloying Microstructure and the CorrosionProtection of Cast Magnesium Alloys

Project: Research project

Description

Weight reduction of vehicles is one strategy to reduce our dependence on petroleum and is also a very important issue for electric vehicles (all EVs or hybrids). Mg the eight most abundant material is the lightest structural metal and its alloys have emerged as an important material for lightweight vehicles. Reduction of vehicle weight directly impacts transportation sector petroleum consumption. Mg is also one of the most electrochemically active metals and consequently its uses historically have been limited. Since the evolution of more modern processing techniques and the realization that deleterious impurity levels could be controlled by minor alloy additions, Mg alloys have once again excited considerable interest in a variety of applications connected to the transportation sector owing to their low density. Nevertheless, there are still outstanding corrosion issues connected to the use of Mg alloys as structural components in automobiles. Our proposal aims at developing a general scientific and engineering framework within which Mg alloy corrosion can be understood, mitigated and predicted. The overall objective of this project is to develop the scientific foundations for understanding the corrosion behaviors of cast Magnesium-Aluminum alloys. The principles and methodologies developed in this program should be useful to the engineer in developing future cast magnesium alloys with superior corrosion resistance for automotive applications. This project has two specific objectives: First, to elucidate the role of alloy microstructure in terms of composition and distribution of the metallurgical phases on the corrosion behavior of representative alloys such as AZ91D and AM60B. Second, to develop corrosion protection coatings using two approaches. One approach involves the use of hydrophobic ionic liquid electrolytes and the other is aimed at the development of stainless steel-like self-healing magnesium alloys via suitable addition of minor alloying elements. This project, which is entirely conducted on the campus of Arizona State University, entails a research program encompassing a combined experimental and computational approach for developing a scientific understanding of the effects of composition and phase distribution on the corrosion behavior of Mg-Al alloys systems. In order to study these behaviors we aim to pursue three general approaches. (1) The use of artificial or synthetic Mg alloys. (2) The use of ionic liquid electrolytes to clarify the anodic dissolution behaviors of the phases without the occurrence of corresponding reactions such as water or di-oxygen reduction. (3) Kinetic Monte Carlo simulations incorporating realistic interatomic potentials and local pH changes to model the effects of dealloying and the spatial redistribution of alloying elements during corrosion. The other major focus of our project will be aimed at developing corrosion protection schemes for these alloys and in this regard we will pursue two paths: (1) The development of hydrophobic coatings using ionic liquids and (2) the development of stainless steel-like Magnesium- Aluminum alloys.
StatusFinished
Effective start/end date10/1/139/30/17

Funding

  • DOE: National Energy Technology Laboratory (NETL): $499,961.00

Fingerprint

Magnesium alloys
Microstructure
Corrosion
Ionic liquids
Corrosion protection
Alloying elements
Petroleum transportation
Aluminum alloys
Stainless steel
Structural metals
Electrolytes
Coatings
Hybrid vehicles
Chemical analysis
Automobiles
Corrosion resistance
Dissolution
Crude oil
Impurities
Engineers