The effect of two-step thermomechanical process on the machanical properties of Al-Mg-Sc alloy.
Date Issued
2006
Date
2006
Author(s)
Tsai, Han-Lung
DOI
zh-TW
Abstract
This study was to investigate the influence of different rolling conditions, such as the two-step thermomechanical process（TMP） and cold rolling, on the tensile properties of Al-Mg-Sc alloy at room temperature and high temperature. The microstructure, annealing characteristics, mechanical properties and superplastic properties of this alloy were studied by using differential thermal analysis（DTA）, microhardness measurements, SEM, TEM and tensile test .
The maximum tensile elongations found in Al-6Mg-0.81Mn -0.4Sc-0.13Zr(wt％) alloy at 530 ℃ is 465％ which occurred under a strain rate of 5×10-3/s. The main deformation mechanism of this material which was produced by a treatment of TMP is grain boundary sliding （GBS） with a high strain rate sensitivity of m=0.48；the sample produced by cold rolling is mainly controlled by the solute-drag mechanism due to a smaller strain rate sensitivity of m= 0.25. It indicates that different rolling conditions affect the deformation mechanism of materials.
It is noted that the strength mechanism and microstructure characteristics are controlled by Al3（Sc,Zr）precipitates which react with dislocations. The experimental results show that Al3（Sc,Zr）particles exhibit structure strengthening, coherent strengthening and the Orowan mechanism.
Subjects
熱機處理
鋁鎂合金
鈧
超塑性
TMP
Al-Mg alloy
Sc
superplasticity
Type
thesis
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