Accession Number : ADA113500

Title :   Non-Destructive Evaluation of Defects in Structural Materials Using Long-Wavelength Neutrons.

Descriptive Note : Annual rept. no. 3, Nov 80-Dec 81,

Corporate Author : NAVAL RESEARCH LAB WASHINGTON DC

Personal Author(s) : Fatemi,M ; Rath,B B

PDF Url : ADA113500

Report Date : 02 Apr 1982

Pagination or Media Count : 37

Abstract : Small-angle neutron scattering (SANS) measurements have been performed on several structural alloys to study voids and microporosities in powder consolidates of Al- and Fe-base alloys. The evolution of precipitates in Al-4%Cu and in beta-III Ti (Ti-11Mo-7Zr-5Sn-0.08Fe-.015C-0.012-0.1O) alloys subjected to varying annealing temperatures and times, and the nucleation and growth of voids formed during creep and superplastic forming in (Cu-3Al-2Si-.5Zn-0.4Co) alloys. The theta'' to theta' phase transformation in Al-4%Cu has been measured and analyzed. Calculated size density distributions show the coarsening of theta' phase with simultaneous disappearance of theta'' as a function of annealing times at 190 C. From these observations, the average size of precipitates at each stage has been calculated and compared with electron micrographic results. Similarly the precipitation of omega-phase in beta-III titanium has been observed for several annealing temperatures (600 F to 800 F) and aging times (2 min. to 100 hrs.). The observation of pronounced peaks in the small-angle profiles leads to an evaluation of the coherence length resulting from a clustering of precipitates. Microporosity in powder consolidates has been studied in two alloys: (Fe-21Cr-6Ni-9Mn-0.02C-0.25N (Wt%)) and Ti-6Al-4V. The analysis shows a variation of Guinier slopes consistent with the expectations of pore size and density variation as a function of the compaction pressure and temperature. Finally, preliminary measurements on superplastically deformed alloys of (Cu-3Al-2Si-.5Zn-.4Co) have been made under varying conditions of strain and strain rates to determine creep-induced void densities.

Descriptors :   *Nondestructive testing, *Defects(Materials), *Neutron scattering, *Long wavelengths, Strain rate, Structural analysis, Deformation, Annealing, Creep, Voids, Porosity, Microstructure, Phase transformations, Precipitates, Construction materials

Subject Categories : Printing and Graphic Arts
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE