Analysis of formation and growth of the σ phase in additively manufactured functionally graded materials

JOURNAL OF ALLOYS AND COMPOUNDS

卷:814

Article

Bobbio, Lourdes D.¹  Bocklund, Brandon¹  Reichardt, Ashley²  Otis, Richard³  Borgonia, John Paul³  Dillon, Robert Peter³  Shapiro, Andrew A.³  McEnerney, Bryan W.³  Hosemann, Peter²  Liu, Zi-Kui¹  Beese, Allison M.^1,4 

[1] Penn State Univ, Dept Mat Sci & Engn, University Pk, PA 16802 USA

[2] Univ Calif Berkeley, Dept Nucl Engn, Berkeley, CA 94720 USA

[3] CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA

[4] Penn State Univ, Dept Mech Engn, University Pk, PA 16802 USA

关键词: Metals and alloys;    Intermetallics;    Laser processing;    Microstructure;    Thermodynamic modeling;    Kinetics;   

DOI  :  10.1016/j.jallcom.2019.151729

来源: Elsevier

【 摘 要 】

This study focuses on the formation of the sigma phase in three functionally graded material (FGM) systems made by additive manufacturing (AM): stainless steel 420 (SS420) to V to Ti-6Al-4V, Ti-6Al-4V to V to stainless steel 304 L (SS304L), and SS420 to V. Directly joining Ti-6Al-4V and stainless steel may result in the formation of brittle Fe-Ti intermetallics. This study investigates the potential use of V as an intermediate element between terminal alloys of Ti-6Al-4V and stainless steel. Experimental analysis of the elemental and phase composition revealed that different amounts of s phase were present in the three FGM systems at locations with similar elemental compositions. Computational studies were performed to simulate the thermal history, phase transformation kinetics, and s phase growth within these FGMs. The computations suggested that, at the conditions studied, the s phase should nucleate faster and grow to a larger volume fraction in the SS420-V alloy than the SS304L-V alloy, contrasting with experimental observations. Instead, experimental analysis confirmed that the disparate growth of s phase in the FGMs was due differences in cracking during fabrication, resulting in different amounts of time spent at the elevated temperatures conducive to s phase growth in each of the samples. (C) 2019 Elsevier B.V. All rights reserved.

【 授权许可】

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