Evolution of the mechanical properties of a cobalt-based alloy under thermal shocks

Junxia Wen; Hongyan Che; Rui Cao; Hao Dong; Youxiong Ye; Haiyan Zhang; Jamieson Brechtl; Yanfei Gao; Peter K. Liaw

doi:10.1016/j.matdes.2019.108425

Evolution of the mechanical properties of a cobalt-based alloy under thermal shocks

Junxia Wen, Hongyan Che, Rui Cao, Hao Dong, Youxiong Ye, Haiyan Zhang, Jamieson Brechtl, Yanfei Gao, Peter K. Liaw

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

10 Scopus citations

Abstract

A cobalt-base alloy manufactured by hot isostatic pressing sintering (HIP) was investigated in the present work. A series of quenching thermal-shock experiments were carried out to study the effects of thermal-cycle shocks on this new cobalt-based alloy. Scanning Electron Microscope (SEM) and Energy Dispersion Spectrum (EDS) were employed to observe the evolution of microstructures under thermal-shock cycles. Results show that some floccus Co₃W₃C precipitated around the WC particles after several thermal-shock cycles. These precipitates and the carbide particles correspond to the locations with the high-stress concentration. The mechanical properties evolution under thermal-shock cycles was analyzed by Nanoindentation tests. The nanohardness presents no noticeable change with thermal-shock cycles. However, the reduced modulus demonstrates a decreasing trend with the thermal-shock cycles. The variation of the mechanical properties has an unestimated relationship with the residual stress and densities of dislocations caused by thermal shocks. Furthermore, the present work pointed out that the precipitates around the carbides are the places where the thermal fatigue crack initiated. How to deal with the precipitates will be the optimized way for this material.

Original language	English
Article number	108425
Journal	Materials and Design
Volume	188
DOIs	https://doi.org/10.1016/j.matdes.2019.108425
State	Published - Mar 2020
Externally published	Yes

Funding

This investigation was supported by the National Natural Science Foundation of China (Nos. 51761027, 51675255). J.X. Wen very much thanks to the support from the excellent students studying abroad foundation of Lanzhou University of Technology. We would also like to thank Dr. T. Dai for his comments. Y.X. Ye would also like to acknowledge funding from the State of Tennessee and Tennessee Higher Education Commission (THEC) through their support of the Center for Materials Processing (CMP). PKL very much appreciates the support of the National Science Foundation (DMR-1611180 and 1809640) with the program directors, Drs. G. Shiflet and D. Farkas. This investigation was supported by the National Natural Science Foundation of China (Nos. 51761027 , 51675255 ). J.X. Wen very much thanks to the support from the excellent students studying abroad foundation of Lanzhou University of Technology. We would also like to thank Dr. T. Dai for his comments. Y.X. Ye would also like to acknowledge funding from the State of Tennessee and Tennessee Higher Education Commission (THEC) through their support of the Center for Materials Processing (CMP). PKL very much appreciates the support of the National Science Foundation ( DMR-1611180 and 1809640 ) with the program directors, Drs. G. Shiflet and D. Farkas.

Funders	Funder number
State of Tennessee and Tennessee Higher Education Commission
THEC
National Science Foundation	DMR-1611180
Directorate for Mathematical and Physical Sciences	1809640
Center for Advanced Materials Processing, Clarkson University
National Natural Science Foundation of China	51761027, 51675255
Lanzhou University of Technology
National Aerospace Science Foundation of China

Keywords

Cobalt-based alloy
Nanoindentation test
Thermal shocks

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10.1016/j.matdes.2019.108425

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title = "Evolution of the mechanical properties of a cobalt-based alloy under thermal shocks",

abstract = "A cobalt-base alloy manufactured by hot isostatic pressing sintering (HIP) was investigated in the present work. A series of quenching thermal-shock experiments were carried out to study the effects of thermal-cycle shocks on this new cobalt-based alloy. Scanning Electron Microscope (SEM) and Energy Dispersion Spectrum (EDS) were employed to observe the evolution of microstructures under thermal-shock cycles. Results show that some floccus Co3W3C precipitated around the WC particles after several thermal-shock cycles. These precipitates and the carbide particles correspond to the locations with the high-stress concentration. The mechanical properties evolution under thermal-shock cycles was analyzed by Nanoindentation tests. The nanohardness presents no noticeable change with thermal-shock cycles. However, the reduced modulus demonstrates a decreasing trend with the thermal-shock cycles. The variation of the mechanical properties has an unestimated relationship with the residual stress and densities of dislocations caused by thermal shocks. Furthermore, the present work pointed out that the precipitates around the carbides are the places where the thermal fatigue crack initiated. How to deal with the precipitates will be the optimized way for this material.",

keywords = "Cobalt-based alloy, Nanoindentation test, Thermal shocks",

author = "Junxia Wen and Hongyan Che and Rui Cao and Hao Dong and Youxiong Ye and Haiyan Zhang and Jamieson Brechtl and Yanfei Gao and Liaw, {Peter K.}",

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AU - Che, Hongyan

AU - Cao, Rui

AU - Dong, Hao

AU - Ye, Youxiong

AU - Zhang, Haiyan

AU - Brechtl, Jamieson

AU - Gao, Yanfei

AU - Liaw, Peter K.

PY - 2020/3

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N2 - A cobalt-base alloy manufactured by hot isostatic pressing sintering (HIP) was investigated in the present work. A series of quenching thermal-shock experiments were carried out to study the effects of thermal-cycle shocks on this new cobalt-based alloy. Scanning Electron Microscope (SEM) and Energy Dispersion Spectrum (EDS) were employed to observe the evolution of microstructures under thermal-shock cycles. Results show that some floccus Co3W3C precipitated around the WC particles after several thermal-shock cycles. These precipitates and the carbide particles correspond to the locations with the high-stress concentration. The mechanical properties evolution under thermal-shock cycles was analyzed by Nanoindentation tests. The nanohardness presents no noticeable change with thermal-shock cycles. However, the reduced modulus demonstrates a decreasing trend with the thermal-shock cycles. The variation of the mechanical properties has an unestimated relationship with the residual stress and densities of dislocations caused by thermal shocks. Furthermore, the present work pointed out that the precipitates around the carbides are the places where the thermal fatigue crack initiated. How to deal with the precipitates will be the optimized way for this material.

AB - A cobalt-base alloy manufactured by hot isostatic pressing sintering (HIP) was investigated in the present work. A series of quenching thermal-shock experiments were carried out to study the effects of thermal-cycle shocks on this new cobalt-based alloy. Scanning Electron Microscope (SEM) and Energy Dispersion Spectrum (EDS) were employed to observe the evolution of microstructures under thermal-shock cycles. Results show that some floccus Co3W3C precipitated around the WC particles after several thermal-shock cycles. These precipitates and the carbide particles correspond to the locations with the high-stress concentration. The mechanical properties evolution under thermal-shock cycles was analyzed by Nanoindentation tests. The nanohardness presents no noticeable change with thermal-shock cycles. However, the reduced modulus demonstrates a decreasing trend with the thermal-shock cycles. The variation of the mechanical properties has an unestimated relationship with the residual stress and densities of dislocations caused by thermal shocks. Furthermore, the present work pointed out that the precipitates around the carbides are the places where the thermal fatigue crack initiated. How to deal with the precipitates will be the optimized way for this material.

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Evolution of the mechanical properties of a cobalt-based alloy under thermal shocks

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Keywords

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