Effects of Minute Addition of Ni on Microstructure and Mechanical Properties of Sn-Zn Eutectic Alloy

Pandey, P and Tiwary, CS and Chattopadhyay, K (2016) Effects of Minute Addition of Ni on Microstructure and Mechanical Properties of Sn-Zn Eutectic Alloy. In: JOURNAL OF ELECTRONIC MATERIALS, 45 (10). pp. 5468-5477.

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Abstract

The current work explores the effects of a small addition of Ni on the microstructure and mechanical properties of Sn-Zn eutectic solder alloy (Sn-14.9 at.%Zn). In two sets of experiments, Ni is either added to the eutectic alloy or Zn in the eutectic alloy is replaced by an increasing amount of Ni. The study indicates that small additions of Ni in eutectic Sn-Zn solder (similar to 0.017 at.%) refines the eutectic microstructure together with the appearance of the small amount of primary Zn plates. Increasing the Ni content to 0.142 at.% and beyond, an intermetallic phase gamma-Ni5Zn21 with dendritic morphology appears in the microstructure along with dendrites of primary Sn. The scale of eutectic microstructure shows a decreasing trend till 0.902 at.%Ni with eutectic spacing of 1.98 +/- 0.12 lm for this alloy. Further addition of Ni coarsens the microstructure. The replacement of Zn with Ni in the eutectic composition follows a similar trend with a lesser refinement of the microstructure. In both the scenarios, the addition of a small amount of Ni increases the eutectic temperatures till a critical concentration is reached beyond which one can observe a decrease in the eutectic point. The trend is similar for the solid solubility of Zn in Sn while the trend is opposite for the measured eutectic composition, which decreases at the initial stages of Ni addition. Through a detailed measurement of mechanical properties, the study establishes significant improvement of the strength of Sn-Zn solder with small additions of Ni in the alloy with a maximum hardness of 26 +/- 2 HV and 0.2% proof stress of 72 +/- 3 MPa at room temperature for the eutectic alloy with 0.902 at.%Ni.

Item Type:	Journal Article
Publication:	JOURNAL OF ELECTRONIC MATERIALS
Additional Information:	Copy right for this article belongs to the SPRINGER, 233 SPRING ST, NEW YORK, NY 10013 USA
Department/Centre:	Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited:	22 Oct 2016 09:14
Last Modified:	22 Oct 2016 09:14
URI:	http://eprints.iisc.ac.in/id/eprint/54995

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