Application of ultrasonic nanocrystal surface modification (UNSM) technique for surface strengthening of titanium and titanium alloys: a mini review

Titanium and titanium alloys have been restricted in tribology-related field, because of their disadvantages, such as low surface hardness, high friction coefficient and poor wear resistance. Various surface modification techniques have been applied to improve their deficiencies. As a new technology of severe surface plastic deformation, ultrasonic nanocrystal surface modification (UNSM) technique has been widely used to realize the surface...