Accession Number : AD0764282

Title :   Correlation of X-Ray and Electron Microscopic Studies of Fatigue.

Descriptive Note : Final rept. 1 Apr 70-31 Mar 73,

Corporate Author : UTAH UNIV SALT LAKE CITY DIV OF MATERIALS SCIENCE AND ENGINEERING

Personal Author(s) : Byrne,J. Gerald

Report Date : 12 JUL 1973

Pagination or Media Count : 7

Abstract : The fatigue behavior of Ni, Ni - 20% Co, and Ni - 60 wt % Co alloys is closely related to their stacking fault energies (SFE) which decrease with increasing % Co. Transmission electron microscopy (TEM) showed that well defined regular subgrains formed in Ni, and progressively more irregular subgrains formed in the alloys as the SFE decreased. TEM subgrain sizes correlated within a factor of two with subgrain sizes previously determined by X-ray diffraction; i.e., approximately 1000 A by TEM and 500 A by X-ray. Scanning electron microscopy (SEM) showed that in pure Ni, cracks initiated among persistent slip bands in grain interiors while in the lower SFE alloys cracks tended to initiate in twin and grain boundaries. (Modified author abstract)

Descriptors :   (*NICKEL ALLOYS, FATIGUE(MECHANICS)), (*COBALT ALLOYS, FATIGUE(MECHANICS)), ELECTRON MICROSCOPY, X RAY DIFFRACTION, CORRELATION TECHNIQUES

Subject Categories : Metallurgy and Metallography

Distribution Statement : APPROVED FOR PUBLIC RELEASE