Al-Cu-Mg 합금의 석출입자, 특히 S-상 입자들에 의한 변형장의 LACBED 관찰
LACBED observation of strain fields due to precipitates, especially S-phase particles in Al-Cu-Mg alloy
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초록
Al 합금 (Al-2.5Cu-1.5Mg wt.% )의 석출물 특히 S-상 석출입자 (Al2CuMg) 부근의 변형 장 (strain fields)에 대해 LACBED 관찰 연구가 처음으로 수행되었다. 변형 장 강도에 대한 정량적 분석을 위해서는 대응되는 LACBED 패턴 시뮬레이션 필요하다. 이를 위해 S-입자에 대해서 형태가 단순한 as–축을 가진 원기둥 모양을 갖고 변형 장의 격자변위 벡터가 이 축에 수직 방향을 갖는다고 가정했다. 이런 단순한 모델을 가지고 변형 장에 대한 관찰 패턴과 시뮬레이션 사이 합리적인 일치를 얻었다. 그러나 합금의 초기 시효 단계에서는 의미 있는 변형 장이 관측되지 않았다. 따라서 이 실험의 결과로 예상되는 것은 합금의 최대 경도를 갖는 시료에는 S-상 석출 입자들이 Al-모체에 복잡한 변형 장 그물 망을 만들고 이것이 합금 경도에 기여 할 것으로 사료된다.
Abstract
The strain fields due to precipitates, especially S-phase (Al2CuMg) particles in Al-2.5Cu-1.5Mg wt.% alloy were first investigated with Large Angle Convergent Beam Electron Diffraction (LACBED) method. The work involves LACBED pattern simulations to estimate possibly the strength of the strain fields. To do this the morphology of S-particle was optimized as a cylindrical shape with as axis, and the displacement vector of strain fields was assumed to be perpendicular to as axis. With this simple model the reasonable fittings between the observed patterns of the strain fields and simulations were obtained. But in the early aging stage the significant strain fields were not observed. Thus it is expected from this experiment that the strain fields due to S-phase precipitates in the stage with maximum hardness would make a complex networks to possibly contribute to hardiness of the alloy.
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