Inprovement of mechanicahl properties of Al-Li-Zr alloys due to the promoted formation of composite precipitates by using rapid solidification technology

The composition of The plloys in this investigation are Al-Li alloys containing 4 Wt% Li with or1 wt% Zr. The alloys rapidly quenched from The melt into continuous ribbons using jetcasting process by single and twin rolls. these ribbons were mechanichally comminuted to fine powderand then consolidated into bulk compacts by vacuum hot pressing and hot extrusion to wires of 2.0mmin diameter(20:<iota> extrusion tatio). These wires were further drown to wires of 1.5 and 1.6mm indiameters.The were specimes were age-treated in the following；(a) as-drown,(b) pre-aged, 500cx2hrs,(c) single-aged, 190cx16hrs,(d) double-aged，500cx2hrs + 190cx16hrs,(e) doule-aged，500cx72hrs + 190cx16hrs . the age-treated specimens were examind by a transmission electron microscopein order to clarify the nature，size and distribution of precipitatrs.这是发现双重打击是非常有效的formation of composite precipitates，which is a continuous envelope of <delta>' al_3 Li surrounding the <alpha>'- al_3 Zr. the presentinvestigation has shown that the enganced mechanical properties that were obtained were mainly dueto the promoted precipitaition of composite precipitete

The composition of the plloys in this investigation are Al-Li alloys containing 4 Wt% Li with or without 1 wt% Zr. The alloys rapidly quenched from the melt into continuous ribbons using jet casting process by single and twin rolls. these ribbons were mechanichally comminuted to fine powder and then consolidated into bulk compacts by vacuum hot pressing and hot extrusion to wires of 2.0mm in diameter(20:<iota> extrusion tatio). These wires were further drown to wires of 1.5 and 1.6mm in diameters.The were specimes were age-treated in the following;(a) as-drown,(b) pre-aged, 500゜Cx2hrs,(c) single-aged, 190゜Cx16hrs,(d) double-aged, 500゜Cx2hrs+190゜Cx16hrs,(e) doule-aged, 500゜Cx72hrs+190゜Cx16hrs.The age-treated specimens were examind by a transmission electron microscope in order to clarify the nature, size and distribution of precipitatrs. It was found that double-ageing is very effective to the formation of composite precipitates, which is a continuous envelope of <delta>'Al_3Li surrounding the <alpha>'-Al_3Zr. The present investigation has shown that the enganced mechanical properties that were obtained were mainly due to the promoted precipitaition of composite precipitete.