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The Memory Metal - Nickel-Titanium Alloy‌

Nickel-titanium alloy, a unique shape memory alloy, can automatically restore its original shape at specific temperatures, demonstrating remarkable plasticity. This alloy not only possesses distinctive shape memory characteristics but also exhibits excellent properties including wear resistance, corrosion resistance, high damping capacity, and superelasticity.

The phase transformation of nickel-titanium alloy is closely related to its performance. Under the influence of temperature and mechanical stress, the alloy exhibits two distinct crystal structure phases: austenite and martensite. During cooling, it undergoes phase transitions from parent phase to R-phase to martensite phase. The R-phase appears rhombohedral, while austenite displays a cubic structure at high temperatures or under load removal, maintaining hardness and shape stability. Conversely, the martensite phase presents a hexagonal structure at lower temperatures or under loading conditions, showing ductility and repeatability but poorer stability that enables deformation.

Additionally, nickel-titanium alloy demonstrates multiple exceptional properties. Its shape memory characteristic allows automatic recovery of original shape through heating after deformation caused by external forces. Simultaneously, superelasticity enables the material to undergo strain far exceeding elastic limits under stress and recover automatically upon unloading. The alloy also shows sensitivity to oral temperature variations, corrosion resistance comparable to stainless steel wires, and excellent vibration damping characteristics.

In orthodontic applications, nickel-titanium alloy wires are increasingly utilized. Their gentle corrective forces minimize damage to dental roots and periodontal tissues, while the unique chemical composition provides certain anti-toxic properties. Therefore, nickel-titanium alloy undoubtedly represents a special metallic material with broad application prospects.