Temperature and Strain Rate Dependence of the Yield Stress in Al-Sc Alloys
- 저자
- C*ang-Sup Oh, Chang-Suk Han
- 게재저널
- Korean J. Met. Mater
- 키워드
- Korean J. Met. Mater, precipitation, transmission electron microscopy (TEM), Orowan stress
- 개요
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The yield strength of a binary Al-Sc alloy, containing a fine dispersion of coherent L12-Al3Sc precipitates, was measured a function of deformation temperature and strain rate. TEM observation was also made of the precipitation microstructure and deformation-induced dislocation structure. The measured yield strength decreased monotonically with an increasing deformation temperature both for underaged and overaged conditions. TEM observation of the overaged specimens, lightly deformed, revealed dislocation loops surrounding the precipitates, indicating that the controlling process is Orowan bypassing. Up to a critical temperature, modulus compensated yield strength (σ0.2/E) is independent of deformation temperature and agreed well with the Orowan stress, calculated on the basis of the experimentally determined distribution parameters for the spherical precipitates. However, in the higher temperature range, σ0.2/E decreased rapidly. The critical temperature varied with the strain rate. From the analysis based on a diffusion-assisted dislocation climbing process, the apparent activation energy of the softening process was estimated to be 1.1 eV.
- 첨부파일
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