Accession Number : ADA320460

Title :   Mechanisms of Quasi-Brittle Failure in Metals and Intermetallic Compounds.

Descriptive Note : Final rept. 1 Dec 91-30 Nov 94,

Corporate Author : PENNSYLVANIA UNIV PHILADELPHIA

Personal Author(s) : Pope, David P. ; Vitek, Vaclav

PDF Url : ADA320460

Report Date : 24 MAY 1995

Pagination or Media Count : 26

Abstract : This is the final report for this program. Progress was made both on the experimental and theoretical aspects of the program. The experimental results demonstrate that single- and polycrystalline Al3Ti in the Ll2 form (by adding Fe or Cr) is intrinsically brittle; although second phase particles can make it even more brittle. The theoretical portion of the program has produced a new theory of the brittle-to-ductile transition temperature involving dislocation-screening assisted homogeneous dislocation nucleation at the transition. The model provides realistic values of the transition temperature and reduces to the well-known Rice-Thomson model at zero temperature and to the equally well-known Kosterlitz-Thouless model at zero stress.

Descriptors :   *METALS, *ALUMINUM COMPOUNDS, *FAILURE, *BRITTLENESS, *INTERMETALLIC COMPOUNDS, STRESSES, MODELS, PHASE TRANSFORMATIONS, SINGLE CRYSTALS, NUCLEATION, IRON, TRANSITION TEMPERATURE, PARTICLES, DISLOCATIONS, TITANIUM, DUCTILITY, CHROMIUM, TITANATES, POLYCRYSTALLINE.

Subject Categories : Inorganic Chemistry
      Crystallography
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE