University:
McMaster University
Course:
MATLS 2H04 | Introduction to Materials Engineering
Academic year:

2023
Views:

227

Pages:

1
Author:

Sabrina S.

9.7 Precipitation Hardening. How Precipitates Form 3-step heat treatment process small precipitate particles form in the microstructure to not every alloy system can be precipitation hardened & act as obstacles to dislocation motion Requirements alloy must have a high solubility of one component in the other (ideally on the order of several percent) a solubility limit that rapidly decreases in concentration w temp. reduction Steps Solid solution treatment: alloy is heated to the single phase region & held for sufficient time to ensure only one phase is present quenching: this single phase is rapidly cooled, which traps the alloying element in the parent matrix. The new phase is a supersaturated solid solution aging: supersaturated solid solution is heated to & held at temperature for sufficient time to permit diffusion (typically for diffusion in metals we need to be at approx. 0.3-0.4 Tm) during aging. fine precipitates form within the parent grain during further cooling to room temp, these fine precipitates will remain as a stable phase in the microstructure.