Khalid M.HAFEZ
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Masaaki NAKA
材料科学技术（英文）
An ultrasonic wave was applied during brazing of alumina to Cu. First alumina was metallized by applying ultrasonic wave in braze bath. Then the metallized alumina was brazed with Cu using the same filler alloy. The filler used were Zn-Al alloys and Zn-Sn Alloys. The weight percent of Al in filler was ranging between 0, 5%, 10%, respectively. The weight percent of tin in filler was ranging between 0, 30%, 60% and 91%, respectively. The joining mechanism was investigated by measuring the joining strength, hardness and analyzing the microstructure at interface of the joint. The shear strength and microstructure of the joint strongly depend on the filler composition. The effect of ultrasound was derived primarily from acoustic cavitations, impact and friction of the filler against alumina ceramic. This improved the wetting between alumina and the filler, and reflected to improve the joint strength. Another ultrasonic advantage as to reduce of the joining temperature, that reduced the thermal stress in the braze joint.
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Alumina
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Journal of Materials Processing Technology
The crystallization temperatures and other thermal properties have been measured systematically for two ternary Cu-Ni-P and two quaternary Cu-Ni-Sn-P amorphous systems. The dependence of crystallization temperature on the composition for the four alloy systems can not be described basically by the usual used Naka rule. The Gibbs free energy of crystallization can be calculated for the alloy systems with the model proposed by Shu et al. Using the calculated free energy of crystallization, it is still not possible to properly describe all of the crystallization temperatures of the alloy systems. However, it has been found that the correlation between the crystallization temperature and the content of the alloy systems can be reasonably explained by the nucleation and growth rates of a new phase for the classical theory of phase transformation. It has been established that the classical theory of phase transformation can be used to describe the thermal stability of the Cu-based amorphous alloys during their crystallization process. (C) 1999 Published by Elsevier Science S.A. All rights reserved.
关键词:
thermal stability;amorphous alloys;Cu-P based alloy systems;classical;theory of phase transformation;solid-liquid interface;structural model;glasses
