快冷与普通Al-Si钎料钎焊试样中Si元素的扩散行为研究

【作者】 王冠；

【导师】 路文江；

【作者基本信息】 兰州理工大学 ， 材料加工， 2005， 硕士

【摘要】 采用快速凝固的方法制备出了Al-Si合金的薄带钎料。利用x射线衍射(XRD),扫描电子显微镜(SEM),差热分析(DTA)等实验手段测量了薄带的熔点,成份等物性。使用EDS对Si元素的扩散现象进行了观察,初步研究和讨论了普通与快冷Al-Si钎料中Si的扩散机理和扩散能力的区别。研究结果表明:普通钎料和快冷钎料中Si元素在母材基体中的扩散过程基本相同。快冷钎料中Si元素在母材中的扩散速度和深度都远高于普通铸态钎料。快冷钎料晶粒细小,晶界上Si元素多,有利于形成“液相通道”是快冷钎料试样中Si元素扩散速度快的主要原因。 作者进一步对Si元素在液相和固相扩散区域的不同扩散行为进行了研究与探索。研究结果表明:钎料熔化初期Si元素在浓度梯度的驱使下向基体扩散,低熔点组分流向基体而高熔点组分逐渐堆积形成“钎料残余层”。在基体深度方向上,Si元素主要沿基体晶界扩散,且随扩散深度的增加呈明显的线性分布状态。更多还原

【Abstract】 The ribbons of Al-Si alloy have been made out by rapid solidification method. The melting point and the component of the ribbons are measured with X-ray diffraction, EDS and DTA separately. Then the diffuse behavior of Si element is observed with the EDS .The differences of the diffuse ability of Si between the as-cast and rapid solidification Al-Si brazing metal are preliminary investigated and discussed .The results indicated that the diffuse behavior of Si element in matrix is basically same , no matter what it came from rapid solidification or as-cast brazing metal .The diffuse speed and depth of Si element in rapid solidification brazing metal are higher than that in as-cast one . Because the grains of rapid solidification brazing metal are fine and there is more Si element distributes on the grain boundary , a ’liquid phase channel’ is formed . So the diffuse speed of Si element in rapid solidification brazing sample is faster.The author further researches and explores the different diffuse action of element Si in liquid and solid zone .The results indicated that the element Si diffuse toward the substrate driven by the concentration grads in the initial stages of melting.The components with low melting point flow toward the substrate and the phase with high melting point deposit gradually and then form the "remnant brazing metal layer".The element Si diffuses along the grain boundary of the substrate in depth direction and present an obvious linear distributing state with the increasing of the diffusion depth.更多还原