Accession Number : ADA193224

Title :   Processing and Properties of Advanced Aluminum Alloys.

Descriptive Note : Annual rept. 1 Jan-31 Dec 87,

Corporate Author : VIRGINIA UNIV CHARLOTTESVILLE DEPT OF MATERIALS SCIENCE

Personal Author(s) : Wert, John A ; Starke, Edgar A , Jr

PDF Url : ADA193224

Report Date : Feb 1988

Pagination or Media Count : 97

Abstract : This project has as its focus microstructure control and fracture of advanced aluminum alloys. Our progress report is divided into two major parts: Part I which is concerned with the effect of microstructure on the deformation and fracture of advanced aluminum alloys, and Part II which is concerned with the recovery and recrystallization mechanisms that operate during processing of advanced aluminum alloys. Age hardenable aluminum alloys may undergo relatively brittle intergranular fracture at strains from 2 to 10 times smaller than the strain to fracture for pure aluminum. This phenomenon can be explained in broad terms as follows. Within a grain, an advancing dislocation either bypasses the coherent particles it encounters or cuts through them; cutting reduces the effective size of the obstacle, while bypassing the obstacle effectively enlarges it. If the obstacles are cut, the weakened plane will continue to slip and deformation will be localized. As a result, dislocations pile up at the grain boundaries at isolated points; the large associated tensions across the grain boundaries open intergranular cracks which propagate without absorbing much energy.

Descriptors :   *ALUMINUM ALLOYS, *FRACTURE(MECHANICS), *MICROSTRUCTURE, ALUMINUM, BRITTLENESS, COHERENCE, DISLOCATIONS, DEFORMATION, GRAIN BOUNDARIES, PARTICLES, PURITY, RECRYSTALLIZATION, SUBJECT INDEXING, STRAIN RATE, CRACK PROPAGATION, AGE HARDENING, STRAIN(MECHANICS), DUCTILITY, MANGANESE, RECOVERY, ANNEALING

Subject Categories : Properties of Metals and Alloys
      Fabrication Metallurgy

Distribution Statement : APPROVED FOR PUBLIC RELEASE