Structure and property modulation of primary CoSn and peritectic CoSn2 intermetallic compounds through ultrasonicating liquid Sn–10%Co alloy

• Published in: Journal of alloys and compounds 2020-06, Vol.827, p.154297, Article 154297
• Main Authors: Liu, J.M., Zhai, W., Wang, B.J., Ma, X., Yan, P.X., Wei, B.
• Format: Article
• Language: English
• Subjects: Cobalt base alloys; Compressive strength; Diffusion; Grain orientation; Grain refinement; Intermetallic compound; Intermetallic compounds; Peritectic alloys; Peritectic solidification; Phase transitions; Power ultrasound; Solid phases; Solidification; Thickness ratio; Ultrasonic imaging; Ultrasound
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2020.154297

The effects of power ultrasound on the peritectic solidification of binary Sn–10%Co peritectic type alloy were investigated. If introducing ultrasound in the whole solidification process, primary CoSn intermetallic compound which grew as coarse strips with a preferred grain orientation under static condition was considerably refined and exhibited a random orientation distribution. Moreover, the significant increase in thickness ratio of peritectic CoSn2 to primary CoSn compounds indicated that the peritectic transformation was remarkably enhanced. To further reveal the underlying mechanism, power ultrasound was respectively applied to primary phase growth and peritectic transformation stages. As compared with the latter one, the former procedure led to a finer primary CoSn phase and a higher peritectic transformation extent. The results showed that ultrasound induced refinement of primary CoSn phase played the dominant role, while ultrasound accelerated atomic diffusion between primary and peritectic solid phases may also contributed to the enhancement of peritectic transformation. Both the yield strength and ultimate compressive strength of Sn–10%Co alloy were improved after ultrasonic solidification. [Display omitted] •Ultrasound is respectively conducted in different transition stages of peritectic alloy.•Ultrasound boosts peritectic transformation more strikingly in primary phase growth stage.•The refinement of primary phase plays the dominant role in enhancing peritectic transformation.•Compressive performance is improved with ultrasound in any transition stages of alloy.