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Precipitation Embrittlement Studies in Vacuum Melted Iron-Chromium Alloys


Wright, William Vale (1955) Precipitation Embrittlement Studies in Vacuum Melted Iron-Chromium Alloys. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/007T-MG19.


This thesis presents the results of an experimental study on the nature of precipitation embrittlement (475[degrees]C embrittlement) in iron-chromium alloys. Electrical resistance, hardness, tension properties, and microstructure were studied using 19, 25, 34, 42, and 49 per cent chromium-iron vacuum melted alloys. Precipitation embrittlement was found to occur from 450[degrees]C to about 540[degrees]C with the rate of embrittlement increasing with teiriperature. Maximum embrittlement occurs near 500[degrees]C. Increasing the chromium content from 19 to 49 per cent increases the rate and magnitude of precipitation embrittlement. An activation energy of 60,000 cal/mol was established for the process. Precipitation embrittlement was found to be analogous to precipitation hardening in alloys where the formation of a coherent precipitate is responsible for property changes in the alloy. A chromium rich body centered cubic ferrite with slightly larger lattice parameter than the iron rich matrix is proposed as the non-equilibrium coherent precipitate which eventually decomposes to form gross sigma phase.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:(Mechanical Engineering and Physics)
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Mechanical Engineering
Minor Option:Physics
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Duwez, Pol E.
Thesis Committee:
  • Unknown, Unknown
Defense Date:1 January 1955
Record Number:CaltechETD:etd-01272004-092755
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:366
Deposited By: Imported from ETD-db
Deposited On:29 Jan 2004
Last Modified:07 Jul 2023 00:02

Thesis Files

PDF (Wright_wv_1955.pdf) - Final Version
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