Environmentally-assisted grain boundary attack as a mechanism of embrittlement in a nickel-based superalloy

被引：140

作者：

Nemeth, A. A. N. ^{[1
]}

Crudden, D. J. ^{[1
]}

Armstrong, D. E. J. ^{[1
]}

Collins, D. M. ^{[1
]}

Li, K. ^{[1
]}

Wilkinson, A. J. ^{[1
]}

Grovenor, C. R. M. ^{[1
]}

Reed, R. C. ^{[1
]}

机构：

[1] Univ Oxford, Dept Mat, Parks Rd, Oxford OX1 3PJ, England

来源：

ACTA MATERIALIA | 2017年 / 126卷

基金：

英国工程与自然科学研究理事会;

关键词：

Ni-based superalloy; Oxidation; Environmentally-assisted cracking; Ductility minima; FATIGUE-CRACK-GROWTH; STRAIN-RATE; INTERGRANULAR CRACKING; YIELD-STRESS; TEMPERATURE; OXIDATION; ALLOY; MICROSTRUCTURE; DEFORMATION; DEPENDENCE;

D O I：

10.1016/j.actamat.2016.12.039

中图分类号：

T [工业技术];

学科分类号：

08 ;

摘要：

The loss of ductility in the high strength polycrystalline superalloy 720Li is studied in air between room temperature and 1000 degrees C. Tensile ductility is influenced profoundly by the environment, leading to a pronounced minimum at 750 degrees C. A relationship between tensile ductility and oxidation kinetics is identified. The physical factors responsible for the ductility dip are established using energy-dispersive X-ray spectroscopy, nanoscale secondary ion mass spectrometry and the analysis of electron back scatter diffraction patterns. Embrittlement results from internal intergranular oxidation along the gamma-grain boundaries, and in particular, at incoherent interfaces of the primary gamma' precipitates with the matrix phase. These fail under local microstresses arising from the accumulation of dislocations during slip assisted grain boundary sliding. Above 850 degrees C, ductility is restored because the accumulation of dislocations at grain boundaries is no longer prevalent. (C) 2017 Acta Materialia Inc. Published by Elsevier Ltd.

引用

页码：361 / 371

页数：11

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