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Effect of Zn, Au, and In on the polymorphic phase transformation in Cu6Sn5 intermetallics

Published online by Cambridge University Press:  31 July 2012

Guang Zeng*
Affiliation:
Nihon Superior Centre for the Manufacture of Electronic Materials (CMEM), School of Mechanical and Mining Engineering, The University of Queensland, Brisbane, Queensland 4072, Australia
Stuart D. McDonald
Affiliation:
Nihon Superior Centre for the Manufacture of Electronic Materials (CMEM), School of Mechanical and Mining Engineering, The University of Queensland, Brisbane, Queensland 4072, Australia
Qinfen Gu
Affiliation:
Powder Diffraction Beamline, The Australian Synchrotron, Clayton, Victoria 3168, Australia
Kazuhiro Nogita
Affiliation:
Nihon Superior Centre for the Manufacture of Electronic Materials (CMEM), School of Mechanical and Mining Engineering, The University of Queensland, Brisbane, Queensland 4072, Australia
*
a)Address all correspondence to this author. e-mail: [email protected]
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Abstract

Cu6Sn5 is a critical intermetallic compound in soldering operations. Conventional equilibrium phase diagrams show that this compound is of either a hexagonal or monoclinic structure at temperatures above and below 186 °C, respectively. Under nonequilibrium conditions, the crystal structure is dependent on composition, temperature, and processing history. The effect of Zn, Au, and In on the hexagonal to monoclinic polymorphic transformation in Cu6Sn5 intermetallics is investigated using variable temperature synchrotron powder x-ray diffraction and differential scanning calorimetry. It is revealed that, as in the case of trace Ni additions, the alloying elements Zn and Au completely stabilize the hexagonal Cu6Sn5 and prevent the phase transformation. In contrast, In additions only partially stabilize the hexagonal Cu6Sn5.

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Articles
Copyright
Copyright © Materials Research Society 2012

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