Wright, William Vale (1955) Precipitation embrittlement studies in vacuum melted iron-chromium alloys. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechETD:etd-01272004-092755
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.))|
|Degree Grantor:||California Institute of Technology|
|Division:||Engineering and Applied Science|
|Major Option:||Mechanical Engineering|
|Thesis Availability:||Public (worldwide access)|
|Defense Date:||1 January 1955|
|Default Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Imported from ETD-db|
|Deposited On:||29 Jan 2004|
|Last Modified:||26 Dec 2012 02:29|
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