Though aluminum's light weight and resistance to corrosion makes it an important component in car manufacturing, one of its major weaknesses is, well, weak spots.
Weak spots develop in aluminum due to repeated, alternating stress, leading to potentially catastrophic engineering alloy failures.
Now, scientists in Australia have come up with a solution to this so-called "failure by fatigue." By modifying the microstructure of aluminum alloys they were able to demonstrate that they can heal these weak spots themselves.
"Eighty percent of all engineering alloy failures are due to fatigue," Monash University Professor Christopher Hutchinson, who led the research, explained in a press release via NewAtlas. "Fatigue is failure due to alternating stress and is a big deal in the manufacturing and engineering industry."
The first-of-its-kind research carried out by Hutchinson and his team focused on the underlying cause of this fatigue, called precipitate free zones (PFZs). These are weak links in aluminum alloys formed by alternating stress. They start out as tiny spots of plasticity and go on to form cracks that eventually fracture the material.
Impressively, the team came up with a method for capturing new particles that form as stress is applied to the aluminum alloy. They were able to use these captured particles to strengthen the weak points. In doing so, they significantly delayed the emergence of fractures.
Mimicking aluminum strain
Their method involves a "training" process that mimics the strains that are placed on the material, repeated over hundreds of cycles so as to accumulate a high concentration of fine particles in the weak zones and enhance the tensile strength of the material.
"Our research has demonstrated a conceptual change in the microstructural design of aluminum alloys for dynamic loading applications," Hutchinson explained. "Instead of designing a strong microstructure and hoping it remains stable for as long as possible during fatigue loading, we recognized that the microstructure will be changed by the dynamic loading and, hence, designed a starting microstructure (that may have lower static strength) that will change in such a way that its fatigue performance is significantly improved."
The researchers say that by modifying the metal's starting microstructure in this way, they can significantly improve the fatigue life of aluminum alloys. High-strength aluminum alloys, which are known for having poor fatigue strength, could have their fatigue life extended by as much as 25 times.