Precipitation in Al-Zn-Mg-Cu Alloys Modified With Sc and Zr During Aging (Preprint)
UES INC DAYTON OH
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This paper was developed under a SBIR contract. The effect of Sc additions on precipitation strengthening in AI-Zn-Mg-Cu alloys was studied after natural and artificial aging. Phase analysis was performed using transmission electron microscopy and computer simulations. Microhardness of the alloys was studied after different steps of aging and the strengthening mechanisms were discussed. It was found that Sc does not affect the kinetics of aging at room temperature, which is controlled by formation and growth of GPI zones. Sc also does not affect the kinetics of aging at 150C, which is controlled by formation and growth of eta and eta particles. However, the additions of Sc accelerate the aging process at l20C within a period of time of formation and growth of GPII zones. It is concluded that the presence of Sc accelerates formation and growth of GPII zones in the Al-Zn-Mg-Cu alloys during artificial aging.
- Properties of Metals and Alloys