Accession Number:

ADA535527

Title:

Precipitation Under Cyclic Strain in Solution-Treated Al-4wt%Cu I: Mechanical Behavior

Descriptive Note:

Conference paper

Corporate Author:

LOS ALAMOS NATIONAL LAB NM MATERIALS SCIENCE AND TECHNOLOGY DIV

Personal Author(s):

Report Date:

2009-02-01

Pagination or Media Count:

7.0

Abstract:

Solution-treated Al-4wtCu was strain-cycled at ambient temperature and above, and the precipitation and deformation behaviors investigated by TEM. Anomalously rapid growth of precipitates appears to have been facilitated by a vacancy super-saturation generated by cyclic strain and the presence of a continually refreshed dislocation density to provide heterogeneous nucleation sites. Texture effects as characterized by Orientation Imaging Microscopy appear to be responsible for latent hardening in specimens tested at room temperature, with increasing temperatures leading to a gradual hardening throughout life due to precipitation. Specimens exhibiting rapid precipitation hardening appear to show a greater effect of texture due to the increased stress required to cut precipitates in specimens machined from rolled plate at an angle corresponding to a lower average Schmid factor. The accelerated formation of grain boundary precipitates appears to be partially responsible for rapid inter-granular fatigue failure at elevated temperatures, producing fatigue striations and ductile dimples coexistent on the fracture surface.

Subject Categories:

  • Properties of Metals and Alloys
  • Fabrication Metallurgy
  • Crystallography

Distribution Statement:

APPROVED FOR PUBLIC RELEASE