Ambient-temperature mechanical properties of isochronally aged 1420-Sc-Zr aluminum alloy

摘要

Ambient-temperature mechanical properties of isochronally aged 1420-Sc-Zr aluminum alloy were investigated. A significant grain refinement is caused with the additions of Sc and Zr. No primary Al-3 Sc or Al3Zr is found in as-cast 1420-Sc-Zr alloy. However, primary Al-3(Sc,Zr) particles exist in as-cast 1420-Sc-Zr alloy. During the isochronal aging process, these particles of Al3Li, Al3Sc and Al3Zr begin to precipitate at 100 degrees C, 250 degrees C and 450 degrees C, respectively. These precipitation particles make 1420-Sc-Zr alloy obtain three peak microhardness: 845 MPa at 150 degrees C, 1000 MPa at 350 degrees C, and 985 MPa at 500 degrees C. The predicted strengthening increments are contrasted to the measured strengthening increment to confirm the operative precipitation mechanism at different isochronal aging. The shearing mechanism is operating in 1420 and 1420-Sc-Zr alloys aged isochronally to 150 degrees C. A mixed mechanism (the shearing and bypass mechanisms) is predicted to be operative in 1420-Sc-Zr alloy aged isochronally to 350 degrees C. The Orowan strenthening mechanism is operative in 1420-Sc-Zr alloy aged isochronally to 500 degrees C. During isothermal aging at 475 degrees C after aged isochronally to 450 degrees C, 1420-Sc-Zr alloy exhibits excellent thermal stability.