Evaluating Local Primary Dendrite Arm Spacing Characterization Techniques Using Synthetic Directionally Solidified Dendritic Microstructures

Abstract

Microstructure characterization continues to play an important bridge to understanding why particular processing routes or parameters affect the properties of materials. This statement certainly holds true in the case of directionally solidified dendritic microstructures, where characterizing the primary dendrite arm spacing is vital to developing the process-structureproperty relationships that can lead to the design and optimization of processing routes for defined properties. In this work, four series of simulations were used to examine the capability of a few Voronoi-based techniques to capture local microstructure statistics (primary dendrite arm spacing and coordination number) in controlled (synthetically generated) microstructures. These simulations used both cubic and hexagonal microstructures with varying degrees of disorder (noise) to study the effects of length scale, base microstructure, microstructure variability, and technique parameters on the local PDAS distribution, local coordination number distribution, bulk PDAS, and bulk coordination number. The Voronoi tesselation technique with a polygon-side-length criterion correctly characterized the known synthetic microstructures. By systematically studying the different techniques for quantifying local primary dendrite arm spacings, we have evaluated their capability to capture this important microstructure feature in different dendritic microstructures, which can be an important step for experimentally correlating with both processing and properties in single crystal nickel-based superalloys.

On Directional Dendritic Growth and Primary Spacing—A Review

“…In the literature, a significant amount of steady state solidification work is reported that characterises the relationship between primary spacing, alloy composition, C 0 , thermal gradient, G, and tip growth velocity, V [33][34][35][36][37][38][39][40][41]. In directional solidification, the G and V can be independently controlled, so one may study the dependence of λ 1 , on either G (at constant V) or V (at constant G).…”

Automatic Recognition of Dendritic Solidification Structures: DenMap

“…Classical methods to determine the average [ 11 , 12 , 13 ] and local [ 14 , 15 , 16 , 17 , 18 , 19 ] PDAS, all require laborious manual determination of the dendrite cores. The manual counting process takes approximately 20 min to 1.5 h depending on the size of the sample surface and number of dendrites.…”

Patterns in Directionally Solidified Alloys

“…Unknown switch argument. (c)), equilibrium alloy composition, 𝐶 0 , thermal gradient, 𝐺, and tip growth velocity, 𝑉 [43][44][45][46][47][48][49][50][51] . In directional solidification, the 𝐺 and 𝑉 can be independently controlled, so one may study the dependence of 𝜆 1 , on either 𝐺 (at constant 𝑉) or 𝑉 (at constant 𝐺).…”