Editing Shape-memory alloy (section)

{{Short description|Alloy which returns to a preset shape when heated}}

{{Lead too short|date=May 2023}}
In [[metallurgy]], a '''shape-memory alloy''' ('''SMA''') is an [[alloy]] that can be [[cold forming|deformed when cold]] but returns to its pre-deformed ("remembered") shape when heated.  It is also known in other names such as '''memory metal''', '''memory alloy''', '''smart metal''', '''smart alloy''', and '''muscle wire'''.{{citation needed|date=April 2019}} The "memorized geometry" can be modified by fixating the desired geometry and subjecting it to a thermal treatment, for example a wire can be taught to memorize the shape of a coil spring.

Parts made of shape-memory alloys can be lightweight, solid-state alternatives to conventional [[actuator]]s such as [[hydraulic]], [[pneumatic]], and motor-based systems. They can also be used to make [[Hermetic seal|hermetic joints]] in metal tubing, and it can also replace a sensor-actuator closed loop to control water temperature by governing hot and cold water flow ratio.