Hi Nihad,
Thank you for contributing to this discussion! If convenient, could you discuss a couple of your comments? Maybe it has been too long since school for me, but I don't get the Tanabe paper on a first read-through. Possibly the translation is an issue as well (they seem to re-define "ionic" and "ionic-like" their own way conveniently). Do you know if the mentions within Tanabe, for instance to "paper 29", are referring to the Proceedings it was published in? The references listed at the end of the paper do not go that high. While aluminum of that purity seems to me of academic/research interest only, stating that no work hardening occurs in 6-nines aluminum is a remarkable statement attributed to this paper 29; work hardening is certainly used in aluminum grade 1350, which is 2.5 to 3-nines purity. So that would be an interesting read as well. I would love to hear a reasoned debate between Tanabe/Yamamoto and a proponent of dislocation theory and alloy design by orbitals. I might even be able to follow part of it.
After writing the above, I did find a paper through a Google search,
Work Hardening and Softening of 4-6N Aluminum in the Processing of Cold Rolling and Heat Treatments, authors Atsushi IKEDA, Kazuhiro YOSHIDA and Mahoto TAKEDAfrom the same Proceedings, which describes how these higher purity aluminums can have both work hardening and softening depending on degree of cold work, purity, and heat treatments. If others are interested it is at
http://www.icaa-conference.net/ICAA12/pdf/P100.pdf This paper doesn't make the assertions of Tanabe et al any more clear to me. I welcome any comments or pointers to references for further reading!
You also mentioned a situation where "SSS is exploited for space nuclear applications to allow the formability of W". Wow, that is an interesting statement. I did not work with refractory metals but am unaware of tungsten being employed structurally, much less being formed for such. Is that process/procedure available in the open literature? Was the W being used for high energy x-ray/gamma shielding?
It's true that in the nuclear field things do get repurposed. I was once called by a client who was apparently researching how to get the heaviest possible material for a balancing counterweight, and wanted to know if I could help them find depleted uranium (!). This is an example of how dangerous non-materials people can be when turned loose with a handbook of values! I suggested that sintered W, just a couple of more letters down the alphabet, would be far more suitable for the usage, was similarly dense, and would not require contacting the military for permits. I didn't even get a chance to address the radiological and health issues of DU before the client decided I was not being helpful enough and ended the exchange. And I never got to find out whether they were successful!
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Paul Tibbals
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Original Message:
Sent: 03-11-2021 12:00
From: Nihad Ben Salah
Subject: Solid Solution Softening in Steel
Hi Stephen,
Very interesting topic!
From what I understand solid-solution softening alloys are alloys where the mechanism of "strengthening" by solid-solution implies the use of solute elements (alloying elements) that has a "smaller bonding environment". We are more familiar with the solid solution hardening where the alloying elements atomic radius is smaller, as C and N in Fe (interstitial SS). However this phenomena does not happen for Ni in Fe, softening occurs. This is a simplistic explanation given to make the phenomena easy to understand, but quantic physics has given a better and more reliable explanation.
First of all, we have to state that Solid solution implies "No Precipitation", thus the amount of solute should be such that the 2 elements are miscible. See, this has something to do with the nature of the chemical bonding of the two elements. Tanabe suggested the use of what it is called the Atomic Bond Population (ABP) of elements to determine the nature of the solid solution they will form (hardening or softening). When 2 elements are bonded, the bond extends in the direction that lowers the energy (the basic nature law), thus the length of the bond is supposed to give the answer. Other explanations were given based on the dislocation theory that we are more familiar to.
As Leslie's diagram you shared is showing, the phenomena is temperature dependent.
I saw a paper where SSS is exploited for space nuclear applications to allow the formability of W.
I am attaching 2010 Tanabe open source paper that gives an insight on the phenomena with the ABP explanation.
So much to say but I'll leave it at this point for now.
Thank you for bringing this topic up.
Nihad
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Nihad Ben Salah
President
NBS- M&P Consulting
Canada
https://www.nbsmpconsult.com/en/home
Original Message:
Sent: 03-10-2021 08:42
From: Stephen Rooney
Subject: Solid Solution Softening in Steel
Hello Everyone!
Last night, I learned of the mechanism of solid solution softening in steel during an evening lecture. This was my first encounter with this phenomenon and am struggling to understand its cause. I have found W.C. Leslie's lecture on substitutional solid solutions in Iron from his 1971 ASM lecture where he described the observed phenomenon in some detail, but is not able to produce a complete explanation of its cause. I've attached a figure from that lecture below.
I thought I might leverage the community to help me on this one. Do we have an explanation for this phenomenon today? I imagine such material behavior would be very important for steels used in space exploration applications and don't doubt that it has been looked into in detail. Any suggestions for good review articles are also welcome!
Thank you!
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Stephen Rooney
R&D Metallurgist
Ellwood Materials Technologies
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