Engineers develop bone-like metal foam that can be `healed` at room temperature
(PHYSorg.com Chemistry)

For 6,000 years, humans have been making things from metal because it`s strong and tough; a lot of energy is required to damage it. The flip side of this property is that a lot of energy is required to repair that damage. Typically, the repair process involves melting the metal with welding torches that can reach 6,300 °F.