Pseudospinodal mechanism for fine α/β microstructures in β-Ti alloys

A. Boyne; D. Wang; R. P. Shi; Y. Zheng; A. Behera; S. Nag; J. S. Tiley; H. L. Fraser; R. Banerjee; Y. Wang

doi:10.1016/j.actamat.2013.10.026

Pseudospinodal mechanism for fine α/β microstructures in β-Ti alloys

A. Boyne, D. Wang, R. P. Shi, Y. Zheng, A. Behera, S. Nag, J. S. Tiley, H. L. Fraser, R. Banerjee, Y. Wang

Research output: Contribution to journal › Article › peer-review

90 Scopus citations

Abstract

Recent experimental observations in β-Ti alloys have demonstrated the formation of a dense population of fine intragranular α precipates when the alloy is step-quenched below a critical temperature. These precipitates are associated with a sudden, significant increase in the apparent nucleation rate. We developed a computational model of α precipitation in Ti alloys, via the phase-field method, in order to investigate the fundamental cause of the observed microstructural changes. We simulated the nucleation of α phase in TiMo for a series of compositions and temperatures and qualitatively reproduced the experimental observations. These results are explained via a pseudospinodal nucleation mechanism: when the system is close enough to the critical point at which the α and β phases have the same free energy, fluctuation-assisted partitionless transformation from β to α becomes the dominant precipitation pathway. Consequently a rapid increase in the nucleation rate occurs, resulting in a fine distribution of numerous intragranular α precipitates.

Original language	English
Pages (from-to)	188-197
Number of pages	10
Journal	Acta Materialia
Volume	64
DOIs	https://doi.org/10.1016/j.actamat.2013.10.026
State	Published - Feb 2014
Externally published	Yes

Funding

The authors would like to acknowledge the financial supports from the US Air Force Research Laboratory (AFRL contract FA8650-08-C-5226) and AFOSR STW-21 Program (Grant No. FA9550-09-1-0014) (R.P.S, H.L.F and Y.W). The authors would also like to acknowledge support from the US National Science Foundation (DMR 1006487) (R.B and H.L.F) and NSF (DMR1008349) (Y.W). In addition, the authors also gratefully acknowledge the Center for the Accelerated Maturation of Materials (CAMM) at the Ohio State University and the Center for Advanced Research and Technology (CART) at the University of North Texas for access to the experimental facilities used for this study.

Keywords

Computer simulation
Congruent transformations
Nucleation
Phase-field method
Precipitation

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10.1016/j.actamat.2013.10.026

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title = "Pseudospinodal mechanism for fine α/β microstructures in β-Ti alloys",

abstract = "Recent experimental observations in β-Ti alloys have demonstrated the formation of a dense population of fine intragranular α precipates when the alloy is step-quenched below a critical temperature. These precipitates are associated with a sudden, significant increase in the apparent nucleation rate. We developed a computational model of α precipitation in Ti alloys, via the phase-field method, in order to investigate the fundamental cause of the observed microstructural changes. We simulated the nucleation of α phase in TiMo for a series of compositions and temperatures and qualitatively reproduced the experimental observations. These results are explained via a pseudospinodal nucleation mechanism: when the system is close enough to the critical point at which the α and β phases have the same free energy, fluctuation-assisted partitionless transformation from β to α becomes the dominant precipitation pathway. Consequently a rapid increase in the nucleation rate occurs, resulting in a fine distribution of numerous intragranular α precipitates.",

keywords = "Computer simulation, Congruent transformations, Nucleation, Phase-field method, Precipitation",

author = "A. Boyne and D. Wang and Shi, {R. P.} and Y. Zheng and A. Behera and S. Nag and Tiley, {J. S.} and Fraser, {H. L.} and R. Banerjee and Y. Wang",

year = "2014",

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doi = "10.1016/j.actamat.2013.10.026",

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T1 - Pseudospinodal mechanism for fine α/β microstructures in β-Ti alloys

AU - Boyne, A.

AU - Wang, D.

AU - Shi, R. P.

AU - Zheng, Y.

AU - Behera, A.

AU - Nag, S.

AU - Tiley, J. S.

AU - Fraser, H. L.

AU - Banerjee, R.

AU - Wang, Y.

PY - 2014/2

Y1 - 2014/2

N2 - Recent experimental observations in β-Ti alloys have demonstrated the formation of a dense population of fine intragranular α precipates when the alloy is step-quenched below a critical temperature. These precipitates are associated with a sudden, significant increase in the apparent nucleation rate. We developed a computational model of α precipitation in Ti alloys, via the phase-field method, in order to investigate the fundamental cause of the observed microstructural changes. We simulated the nucleation of α phase in TiMo for a series of compositions and temperatures and qualitatively reproduced the experimental observations. These results are explained via a pseudospinodal nucleation mechanism: when the system is close enough to the critical point at which the α and β phases have the same free energy, fluctuation-assisted partitionless transformation from β to α becomes the dominant precipitation pathway. Consequently a rapid increase in the nucleation rate occurs, resulting in a fine distribution of numerous intragranular α precipitates.

AB - Recent experimental observations in β-Ti alloys have demonstrated the formation of a dense population of fine intragranular α precipates when the alloy is step-quenched below a critical temperature. These precipitates are associated with a sudden, significant increase in the apparent nucleation rate. We developed a computational model of α precipitation in Ti alloys, via the phase-field method, in order to investigate the fundamental cause of the observed microstructural changes. We simulated the nucleation of α phase in TiMo for a series of compositions and temperatures and qualitatively reproduced the experimental observations. These results are explained via a pseudospinodal nucleation mechanism: when the system is close enough to the critical point at which the α and β phases have the same free energy, fluctuation-assisted partitionless transformation from β to α becomes the dominant precipitation pathway. Consequently a rapid increase in the nucleation rate occurs, resulting in a fine distribution of numerous intragranular α precipitates.

KW - Computer simulation

KW - Congruent transformations

KW - Nucleation

KW - Phase-field method

KW - Precipitation

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DO - 10.1016/j.actamat.2013.10.026

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VL - 64

SP - 188

EP - 197

JO - Acta Materialia

JF - Acta Materialia

ER -

Pseudospinodal mechanism for fine α/β microstructures in β-Ti alloys

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Keywords

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