Traditional fusion welding (via shielded metal arc welding, gas metal arc welding, or gas tungsten arc welding) and resistance spot welding produce a HAZ around the weld area . Recent advanced techniques, such as cold metal transfer joining, reduce heat input, but do not eliminate the HAZ . Some degree of HAZ is even observed in friction stir welding, a solid-state welding technique . In the HAZ, which can span a few millimeters [2,6] or even centimeters [4,7] from the weld perimeter, the metal temperature is substantially increased during the welding process. In age-hardened Al alloys like 6061-T6, heat from welding can lead to overaging of the alloy, causing a loss of material strength . In work-hardened alloys like 5052, strength is reduced by annealing of the material. As a result, materials become more susceptible to failure in the HAZ around the weld.