Investigation of Solidification Pathways in CoSi Alloys.
Barlow, Stanley M.
- Co38.5Si61.5 and Co60Si40 eutectic alloys were melted and solidified on an electrostatic levitator (ESL) at various undercoolings in order to determine their phase transformations along the transition from a liquid to a solid state. Investigation into the solidification velocity of constituent phases identified specific solidification pathways relative to first recalescence undercooling. Results i... read morendicated two different thermal events for both alloys. A critical undercooling of 81.5 K during the first recalescence of Co38.5Si61.5 was established, below which solidification velocity was faster during first recalescence and slower during second recalescence than were respective velocities above the temperature split. A similar critical undercooling of 50 K was found for the Co60Si40 alloy, where similar velocity relationships were observed. It is also speculated that a critical undercooling is necessary during second recalescence following high undercoolings in first recalescence in order to lower the energy required for nucleation to occur. Metallography showed that delay time between recalescence events has an effect on morphology change during solidification. The findings presented in this thesis support prior work done involving similar research with both CoSi eutectic alloys.read less