Accession Number:

ADA522993

Title:

Tensile Deformation and Fracture Mechanism of Bulk Bimodal Ultrafine-Grained Al-Mg Alloy

Descriptive Note:

Journal article

Corporate Author:

CALIFORNIA UNIV BERKELEY LAWRENCE BERKELEY LAB

Report Date:

2010-04-01

Pagination or Media Count:

9.0

Abstract:

The tensile fractures of ultrafine-grained UFG Al-Mg alloy with a bimodal grain size were investigated at the micro- and macroscale using transmission electron microscopy TEM, scanning electron microscopy SEM equipped with focused ion beam FIB, and optical microscopy. The nanoscale voids and crack behaviors near the tensile fracture surfaces were revealed in various scale ranges and provided the evidence to determine the underlying tensile deformation and fracture mechanisms associated with the bulk bimodal metals. The bimodal grain structures exhibit unusual deformation and fracture mechanisms similar to ductile-phase toughening of brittle materials. The ductile coarse grains in the UFG matrix effectively impede propagation of microcracks, resulting in enhanced ductility and toughness while retaining high strength. In view of the observations collected, we propose a descriptive model for tensile deformation and fracture of bimodal UFG metals.

Subject Categories:

  • Properties of Metals and Alloys
  • Test Facilities, Equipment and Methods
  • Mechanics
  • Atomic and Molecular Physics and Spectroscopy

Distribution Statement:

APPROVED FOR PUBLIC RELEASE