Which of the following chrome cobalt wire is highly ductile and become resilient on heating?
Elgiloy wires by Rocky Mountain Orthodontics Company are supplied in four tempers which indicate the level of resilience. The composition of all these tempers is reported to be the same, the difference being in the wire processing methods.

Blue (soft): The blue wire is the softest of the four wire tempers; it can be bent easily into the desired shapes. It is recommended for use, when considerable wire bending is needed such as multiple loop wires.
Yellow (ductile): It is more resilient than blue elgiloy, but can also be bent with relative ease.
Green (semi-resilient): It is more resilient than yellow.
Red (resilient): Red Elgiloy wire is the hardest and most resilient elgiloy and provides high spring qualities. Careful manipulation is recommended when using this wire because it withstands only minimal working. Heat treatment makes red elgiloy remarkably resilient, but brittle.

Reference: Orthodontics: Diagnosis and Management of Malocclusion and Dentofacial Deformities 3rd O P Kharbanda, pdf no 1775
Yellow elgiloy
Blue elgiloy
Green elgiloy
Red elgiloy