Directional solidification of a Sn-0.2Ni solder alloy in water-cooled copper and steel molds: Related effects on the matrix micromorphology, nature of intermetallics and tensile properties

JOURNAL OF ALLOYS AND COMPOUNDS

卷:723

Article

Xavier, Marcella G. C.¹  Cruz, Clarissa B.²  Kakitani, Rafael²  Silva, Bismarck L.³  Garcia, Amauri²  Cheung, Noe²  Spinelli, Jose E.¹ 

[1] Fed Univ Sao Carlos UFSCar, Dept Mat Engn, BR-13565905 Sao Carlos, SP, Brazil

[2] Univ Estadual Campinas, UNICAMP, Dept Mfg & Mat Engn, BR-13083860 Campinas, SP, Brazil

[3] Fed Univ Rio Grande Norte UFRN, Dept Mat Engn, BR-59078970 Natal, RN, Brazil

关键词: Sn-Ni alloys;    Solders;    Directional solidification;    Microstructure;    Intermetallics;    Tensile properties;   

DOI  :  10.1016/j.jallcom.2017.06.329

来源: Elsevier

【 摘 要 】

The present investigation is focused on, firstly, performing transient directional solidification experiments with a Sn-0.2 wt.% Ni solder alloy using two different substrates as mold sheets separating the alloy casting from the cooling fluid: copper and low carbon steel. Secondly, the examination of the obtained microstructures is carried out highlighting not only the micromorphology aspects of the formed beta-Sn phase but also the nature and the shape of the intermetallic compounds (IMCs) developed. The purpose of this research work is to verify the influences that different substrate materials may have on the alloy solidification kinetics, resultant microstructures and tensile properties of the Sn-0.2 wt.% Ni solder. The microstructure characteristics may be correlated with thermal solidification parameters such as the eutectic cooling rate and eutectic growth rate along with a qualitative evaluation of Fe and Cu dissolutions into the alloy. The results display that the dissolution of Cu into the Sn-Ni alloy provided the prevalent growth of the (Cu, Ni)(6)Sn-5 fiber-like eutectic phase along the length of the casting. Other than, the Cu-containing Sn-Ni alloy allowed the growth of high-velocity b-Sn cells only for very high cooling rates, associated with positions closer to the bottom of the alloy casting. Farther positions are characterized by a complex growth of b-Sn dendrites. On the other hand, for the alloy solidified against the steel mold, a predominance of the non-equilibrium NiSn4 eutectic phase with plate-like shape has been identified by SEM/EDS and XRD. In this case, the predominant growth of b-Sn cells associated with the presence of the plates of the NiSn4 IMC allowed lower tensile strength and higher ductility to be attained. (C) 2017 Elsevier B.V. All rights reserved.

【 授权许可】

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