A method to predict the precipitation hardening response of particle strengthened alloys

James Mark Fragomeni, Purdue University

Abstract

This document describes a research project directed toward the development of an approach for predicting the precipitation hardening response of particle strengthened alloys. This document presents two theoretical procedures or methods for predicting the precipitation strengthening response. The first procedure presents a precipitation strengthening model utilizing an aluminum-lithium-zirconium research alloy as the demonstration medium. This model is based on a number of existing models that describe the dislocation mechanics, particle coarsening, and particle shearing and looping mechanisms of precipitation hardened alloys. The model predicts the variation in yield strength with aging time, temperature, and composition for the underaged, peak-aged, and overaged conditions. The development of this model provided the foundation and understanding for the development of a method to predict the precipitation hardening response of particle strengthened alloys from a minimum number of tensile tests. This method eliminates the need for a materials database of tensile properties and also does not require all the values for the different microstructural constants to be known beforehand as did the first procedure. A statistical approach was utilized to help solve the metallurgical problem of predicting the precipitation strengthening response. This method was extended to some other alloys in addition to the aluminum-lithium-zirconium research alloy to provide a vehicle for predicting the precipitation strengthening response.

Degree

Ph.D.

Advisors

Hillberry, Purdue University.

Subject Area

Materials science|Mechanical engineering

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