Yes Donato I agree, in fact the question for aluminum (Campbell's gadfly) in Chin/Hosford/Backofen back in 1964- tensile tests on zone purified aluminum draws to a point if zone purified - see attached. I don't think zone purificaition can remove oxides? also are all coppers completely free of oxygen?even the socalled OF coppers?
Also, P. Bridgeman's work on many metals/alloys tensile tested under hydrostatic pressure - usually drawn to a point - dislocation generated voids around oxides and NMI kept closed - but are these entraped contaminated still active in preventing a metal reaching it projected deformation behavoir that Campbell assests the metal/ally shoudl in the "pure" state?
I think Prof. Campbell raises a few questions that have never been resolved satisfactorly -but simply avoided and addressing simpler issues/questions such as grain size, NMI engineering, composites, indignious precipitates, etc.
------------------------------
Edward Vojcak
Senior Metallurgical Engineer
SGS North America
Blue Island IL
(708) 595-8734
------------------------------
Original Message:
Sent: 04-28-2022 02:00
From: Donato FIRRAO
Subject: Thoughts on Fracture of Metals
Just a question, Edward.
Do not we have the same when pulling a pure Copper wire we are able to activate many subsequent slip system and we break the wire when it is reduced to just a puntiform tip?
------------------------------
Donato FIRRAO FASM
Professor
Politecnico di Torino
TORINO
+393351494032
Italy
Original Message:
Sent: 04-27-2022 09:14
From: Edward Vojcak
Subject: Thoughts on Fracture of Metals
During the pandemic in 2020 a book from John Campbell (Noted casting technology guru) titled "The Mechanisms of Metallurgical Failure - The Origin of Fracture" Butterworth-Heinemann/Elsevier was published and cites a profound Thesis that "entrainment defects" have been overlooked thoughout the history of metallurgy degrading all metals so that they fracture - when as predicted by the electron theory metals/alloys shoudl NEVER fracture - implying redcution in area in a tensile test is a direct measure of the quality of any metal.
The question is if all "entrainment defects" were eliminated that metal and alloys will deform down to nearly a single atom! So one should be able in theory, grip a small section on a chunk of metal (whisker) and pull (drawn) all the metal in the chunk to that size in a long length conserving only mass.
------------------------------
Edward Vojcak
Senior Metallurgical Engineer
SGS North America
Blue Island IL
(708) 595-8734
------------------------------