The Study Of Trace Sc And Heat Treatment On The Organization And Performance Of High Strength Aluminum Alloy

Aimed at the national 973 project, the effects of minor Sc heat treatment on microstructure and mechanical properties, such as σ b, σ 0 2 and 8 under room temperature were studied systematically by means of OM,TEM and SEM. The mechanism of above effects was analyzed. Results of the study are as follows: 1. When the single aging system is T6(120℃x24h), the best mechanical properties and its solution treatment of alloy lσis concluded as follows: 470癈 X 120min 2.When the value of conductivity is not less than 22 Ms/m, the best mechanical properties and its heat treatment of alloy 1σ is concluded as follows: mechanical properties: σb=595.8Mpa, σ0.2=572.0Mpa, 8=8.3%; solution treatment: 470℃ X 120min; RRA: 120℃x24h, 170℃xlh, 120℃x24h;3. Additional of minor Sc and Zr leads to the precipitation of primary Al3(Sc, Zr) particles during solidification, which have a powerful grain refining effect, so the cast grain size of alloy 3σ is much smaller than alloy 2σ.5. Additional of minor Sc and Zr leads to the precipitation of secondary Al3(Sc, Zr) particles d uring h omogenization, w hich h ave a powerful e ffect o n p inning u p t he dislocations and grain boundaries(figure 3-1 l(c)), preventing the grain boundary migration, so the recrystallization temperature is elevated apparently. 5. Due to additional of minor Sc(0.3wt%) , the mechanical properties of alloy 3σ is fine than alloy2σ by different heat treatment:T6(l20σx24h): the ob, o02, 6 are increased by 37.7MPa, 63.5MPa, 0.9% respectively;RRA(120℃x24h, 170℃xlh, 120℃x24h): σb, σ02> 6 are increased by 35.7MPa> 30.1MPa, 2.4% respectively;...