RESEARCHERS from the University of Michigan have found why metal alloys can fail unexpectedly in a range of applications.
This information is vital because alloys are used in many manufactured objects, from jet engines to electronic devices. In some satellites where new lead-free solder was used, these failures caused the formation of ‘tin whiskers’, which damaged the equipment.
Alloys are made from two or more different metallic elements. These metals are mixed together in molten liquid form, and allowed to solidify. This causes the formation of tiny grains of crystal.
Generally, alloys are created because they have advantages over the single metals, because the elements fill in the vacancies of each other’s atomic lattice. This changes the structure of the material.
According to the scientists, the problem arises because atoms of different elements hop around at different rates, depending on the strength of the bond. When the discrepancy in the hop rates is too high, there can be a pronounced diffusion along grain boundaries, leading to faster degradation.
The researchers hope they will be able to find out how to make longer-lasting alloys, by using metals with similar atomic hop rates.
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