Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

On the Properties of Alpha/Alpha + Beta Diffusion Couples

Published

Author(s)

William J. Boettinger, Sam R. Coriell, Carelyn E. Campbell, Geoffrey B. McFadden

Abstract

The properties of diffusion couples in a ternary system are examined theoretically when one end member is composed of single-phase material (alpha) and the other end member is composed of two-phase material (α + Β). Using the model of Morral and co-workers, we examine the cases in which the two-phase region either grows or dissolves. We prove that when the two-phase material grows, there can be no jump in concentration (or phase fraction of Β) at the boundary between the two materials. When it dissolves a jump is necessary. We present numerical examples to demonstrate this result. We also show how the diffusion path varies depending on the composition of the single-phase α end member for a fixed α + Β end member composition. Under some conditions, three solutions are found for the same initial end member compositions. When these multiple solutions exist, either two or three are virtual (path involves supersaturation). Whenever all three solutions are virtual, a single solution with three interfaces can be found. In this case an intermediate layer of α phase forms within the α + Β material to relieve the supersaturation.
Citation
Acta Materialia
Volume
48
Issue
No. 2

Keywords

diffusion, diffusion path, multicomponent, multiphase, multiple solutions, virtual

Citation

Boettinger, W. , Coriell, S. , Campbell, C. and McFadden, G. (2000), On the Properties of Alpha/Alpha + Beta Diffusion Couples, Acta Materialia (Accessed April 22, 2024)
Created January 1, 2000, Updated February 17, 2017