Elevated temperature deformation behavior of a dispersion-strengthened Al-Fe, V, Si alloy

Journal Article · Sun Dec 01 04:00:00 EST 1996 · Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science

DOI:https://doi.org/10.1007/BF02595640· OSTI ID:438556

Mitra, S ^[1]

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1. Hewlett-Packard Co., Santa Clara, CA (United States). Components Group

The deformation behavior of a rapidly solidified, dispersion-strengthened Al alloy containing 11.7 pct Fe, 1.2 pct V, and 2.4 pct Si was studied at test temperatures up to 450 C using constant-stress creep and constant strain-rate tensile tests. Apparent stress exponents (n) up to {approximately}24 and an activation energy of 360 kJ/mol were obtained with the standard Arrhenius type power-law creep equation, which also suggested a change in behavior at {approximately}300 C. Substructure-invariant and dislocation/dispersoid interaction models were found to be inadequate for explaining the behavior. When the data were replotted as {dot {var_epsilon}}{sup 1/n} vs {sigma}, two regimes were found between 350 C and 450 C. A model with a pseudothreshold stress ({sigma}{sub Th{prime}}) for the higher stress regime resulted in n {approximately} 3, indicating solute drag in this regime. Transmission electron microscopy (TEM) showed departure-side pinning of dislocations at higher stresses. In the lower stress regime, TEM showed dislocation subgrain structures. Here, the model resulted in a stress exponent of {approximately}4.5 indicating the dislocation climb mechanism. At temperatures below {approximately}300 C, a single regime was found along with lower activation energies and a stress dependence of {approximately}3. Dislocation pipe diffusion is proposed to explain the lower activation energy. The origin of {sigma}{sub Th{prime}} has been tied to dislocation generation at the grain boundaries.

• Sponsoring Organization: USDOE
• OSTI ID: 438556
• Journal Information: Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science, Journal Name: Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science Journal Issue: 12 Vol. 27; ISSN 1073-5623; ISSN MMTAEB
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ACTIVATION ENERGY
ALUMINIUM BASE ALLOYS
CREEP
DEFORMATION
DISLOCATIONS
GRAIN BOUNDARIES
IRON ALLOYS
MATHEMATICAL MODELS
SILICON ALLOYS
TENSILE PROPERTIES
VANADIUM ALLOYS