Embrittlement of Engineering Alloys Edited by C.L. Briant and S.K. Baneerji ( Volume 25 of Treatise on Materials Science
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PACE 2, MRS BULLETIN, JULY/AUGUST 1986
Embrittlement of Engineering Alloys Edited by C.L. Briant and S.K. Baneerji (Volume 25 of Treatise on Materials Science and Technology, Academic Press, 1983) In view of the p r e s e n t demand for engineering alloys that can withstand extreme service conditions and aggressive environments, this book comes at a very opportune moment. It presents a comprehensive review of the various process and service conditions that lead to degradation of the mechanical properties of common structural materials. The topics, organized in 11 chapters, cover the influence of alloy composition or processing, effects of elevated temperature service, corrosion in air or aqueous environments, and embrittlement by hydrogen, liquid metals, and irradiation. Each chapter provides considerable information and a literature review to allow the reader to pursue specific interests. C h a p t e r 1 by Mulford discusses the susceptibility of nickel toe mbrittlemen t by trace impurities. Recentdata are presented to support the conclusion that embrittlement at t e m p e r a t u r e s below 900°C is primarily due to equilibrium segregation of sulfur and harmful metallic elements (e.g., Bi, Pb, Te, and Se). The effects of grain boundary precipitation of sulfides, intermetallics,etc.,at hot working temperatures (above 900°C), are considered separately. The influence of trace amounts of beneficial elements is also discussed. Chapter 2 by Briant a nd Baneerji covers intergranular fracture in ferrous alloys as a result of grain boundary segregation of embrittling elements. The discussions focus on embrittlement of tempered martensite and temper embrittlement of low-alloy ferritic steels. The embrittling elements and process conditions as well as the beneficial effects of other alloying elements are identified. Finally, results from recent investigations to explain embrittlement from theoretical considerations are presented. The kinetics and thermodynamics of segregation, the mechanics of intergranular fracture, and the role of chemical bonding in grain boundary decohesion are discussed. In Chapter 3, Ritter and Briant describe the effects of second-phase particles on the fracture of engineering alloys. Four classes of structural materials (steels, superalloys, and aluminum and titanium alloys) are discussed. The chapter identifies the secondphase particles involved and provides a mechanistic understanding of the fracture process. The section on steels is primarily devoted to ductile fracture; the role of second-phase particles in brittle cleavage fracture is neglected. The various phases in
superalloys and the conditions for their formation are detailed. The methods of using electron vacancy calculations to predict the formation of the harmful phases in superalloys are also presented. Chapter 4 by Pope deals with the creep behavior of Cr-Mo and Cr-Mo-V ferritic steels. It would have been helpful if the title had reflected the restriction to these steels. Effects of temperature, strain rate, stress, microstructure,
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