Shape-memory alloys can be made from three different combinations, or alloys - a copper-aluminium-nickel alloy, a nickel-titanium alloy, or less commonly, a zinc, copper, gold and iron alloy. The alloy being used in the video above is a nickel-titanium alloy, which is commercially produced as sold as ‘Nitinol’.
“Once heated to the critical temperature, Nitinol shows its 'heat memory' as it transforms into the austenitic state, where the atoms become locked into their previous rigid arrangement,” says the Grand Illusions website. "When the metal springs into its remembered shape, it does so with so much force that it can be used to do actual work. Small motors have been built using Nitinol wire that passes through different temperatures. Solar panels on some satellites are raised into position by shape memory alloys, activated by the heat of the Sun.”
