Auger and x-ray photoelectron spectroscopy study of localized intergranular cracking in a nickel—chromium—molybdenum—iron alloy

✍ Scribed by C. A. Bradbury; K. E. Sturgill; D. C. McKissick

• Publisher: John Wiley and Sons
• Year: 1992
• Tongue: English
• Weight: 585 KB
• Volume: 18
• Category: Article
• ISSN: 0142-2421
• DOI: 10.1002/sia.740180210

✦ Synopsis

Abstract

An unused jet engine tailpipe, fabricated from a nickel—chromium—molybdenum—iron alloy, was found to be severely embrittled after 7 years of storage. Metallurgical and mechanical tests found a larger than specification size grain structure and several very localized areas of unexplained low ductility. These were surrounded by material with normal properties. Auger electron spectroscopy (AES) studies documented the elemental composition and relative concentration at the grain boundaries. Sodium, chlorine, sulfur, iron, chromium, nickel and carbon were present. The concentration of the iron was much higher than expected, while the nickel concentration was significantly lower. The concentrations remained at these levels through 90 min of ion sputtering. X‐ray photoelectron binding energies of iron and carbon indicate that these elements were present as carbides. The presence of an abnormal chemistry at the grain boundaries, such as iron carbides, was considered to be the probable cause of the embrittlement.