TY - JOUR

T1 - Hypo-peritectic TRIS–NPG in a stationary temperature gradient

T2 - Thermodynamics, grain boundary migration and phase identification

AU - Ludwig, Andreas

AU - Mogeritsch, Johann Peter

AU - Witusiewicz, V. T.

N1 - Publisher Copyright: © 2022

PY - 2023/2/15

Y1 - 2023/2/15

N2 - At a stationary temperature gradient, the grain boundaries comprising residual melt can migrate. Their migration is governed by liquid diffusion and, in multiphase materials, depends highly on the phases present. Therefore, this phenomenon can be used for phase identification if data on metastable extensions of the corresponding phase diagram are available. Thus, we re-optimised the thermodynamic description of Tris(hydroxymethyl)aminomethane-Neopentylglycol (TRIS–NPG), a transparent peritectic alloy often used as a model alloy for metallic solidification, and used the predicted metastable liquidus and solidus curves to evaluate the grain boundary migration observations. As we found temperature gradient zone melting (TGZM) at low temperatures, the presence of the peritectic phase could be excluded even though a near-peritectic alloy had been processed. The liquid diffusivity, as a function of the position/temperature, was estimated from the TGZM velocity measurements. The data suggest that the diffusion coefficient deep in the mush is one order of magnitude smaller than that close to the liquidus temperature. This may be typical for non-dilute alloys, where the concentration of the intergranular liquid changes considerably.

AB - At a stationary temperature gradient, the grain boundaries comprising residual melt can migrate. Their migration is governed by liquid diffusion and, in multiphase materials, depends highly on the phases present. Therefore, this phenomenon can be used for phase identification if data on metastable extensions of the corresponding phase diagram are available. Thus, we re-optimised the thermodynamic description of Tris(hydroxymethyl)aminomethane-Neopentylglycol (TRIS–NPG), a transparent peritectic alloy often used as a model alloy for metallic solidification, and used the predicted metastable liquidus and solidus curves to evaluate the grain boundary migration observations. As we found temperature gradient zone melting (TGZM) at low temperatures, the presence of the peritectic phase could be excluded even though a near-peritectic alloy had been processed. The liquid diffusivity, as a function of the position/temperature, was estimated from the TGZM velocity measurements. The data suggest that the diffusion coefficient deep in the mush is one order of magnitude smaller than that close to the liquidus temperature. This may be typical for non-dilute alloys, where the concentration of the intergranular liquid changes considerably.

KW - A1: Directional Solidification

KW - A1: Optical microscopy

KW - A1: Supersaturated solution

KW - A2: Bridgman technique

UR - http://www.scopus.com/inward/record.url?scp=85144617502&partnerID=8YFLogxK

U2 - 10.1016/j.jcrysgro.2022.127052

DO - 10.1016/j.jcrysgro.2022.127052

M3 - Article

AN - SCOPUS:85144617502

VL - 604.2023

JO - Journal of crystal growth

JF - Journal of crystal growth

SN - 0022-0248

IS - 15 February

M1 - 127052

ER -