| Title |
The Effect of ultrasonic Vibrations on the Precipitation hardening of 7075 Al Alloy |
| Authors |
노태환(T . H . Noh); 천성순(S . S . Chun) |
| Abstract |
The effect of ultrasonic vibration on mechanical properties and microstructure of 7075 Al alloy by precipitation hardening has been investigated. Ageing treatment with ultrasonic vibration at 120℃ is improving the mechanical properties such as the yield strength and elongation compared with the conventional ageing treatment. It is believed that ultrasonics produces the excess vacancies and these vacancies are accelerating the formation of GP zones. The formation of GP zones has pronounced effect on the refinement of precipitate particle size and inhibition of PFZ(precipitate free gone) and grain boundary precipitate formation. Ageing at 180℃ with ultrasonic vibration produces directly η´ particle without the formation of GP zone. Therefore it is believed that the excess vacancies formed by ultrasonic vibration do not affect on the refinement of matrix precipitate particle size. |