Observations of the occurrence and disappearance of peritectic couple growth performed under microgravity conditions

Peritectic couple growth (PCG) is an unusual growth form at which the peritectic and pro-peritectic solid phases solidify like a regular eutectic. To investigate the dynamics of PCG formation and growth, experiments with the transparent, organic peritectic alloy Tris(hydroxymethyl)aminomethane-Neopentylglycol are performed at the International Space Station. Fully planar and partly planar/cellular PCGs are found and analyzed. In any case, PCG starts with the formation of lateral bands from the peritectic phase that overgrow most of the pro-peritectic phase but not completely. During coupled growth, the remaining patches transform into rods and/or lamellae. Depending on the conditions, PCG either terminates by the disappearance of pro-peritectic rods or by transforming the rods into cells. The second mechanism goes hand in hand with the formation of a single-phase 2D layer at the top of a tilted interface. At low pulling velocities, planar pro-peritectic phase growth transforms into planar peritectic phase growth via PCG.

Automated summary

Peritectic couple growth (PCG) is an unusual growth form where the peritectic and pro-peritectic solid phases solidify similar to a regular eutectic. Experiments were conducted at the International Space Station to investigate the dynamics of PCG formation and growth using the organic peritectic alloy Tris(hydroxymethyl)aminomethane-Neopentylglycol. Both fully planar and partly planar/cellular PCGs were observed and analyzed. PCG initiates with the formation of lateral bands from the peritectic phase that overgrow most of the pro-peritectic phase but not completely. The remaining patches transform into rods and/or lamellae during coupled growth.