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It's interesting that the new alloy was not recognized by XRF. In the video it looked like they had a large set of standards from which to build an empirical mo

by amatus 11y ago

It's interesting that the new alloy was not recognized by XRF. In the video it looked like they had a large set of standards from which to build an empirical model. I don't know how likely it is that Apple created their own alloy, but I have experience with XRF analysis and I know it's easy to make mistakes preparing a sample. It's possible the tungsten came from the sandpaper used to remove the anodization layer or it might have been part of the anodization layer. Another tricky detail when analyzing materials is how the different elements adhere to the surface. The X-rays only see the atoms at the surface. If sanding the alloy removes more of a softer metal or smears it over the surface covering the other elements you may get inaccurate results.

iaw 11y ago
Do you know if there's been experimentation with tungsten alloying of aluminum in the past? The thing that surprises me here is that if Apple did create an entirely new alloy with novel properties, why weren't those metallurgical characteristics already known? It's not like metallurgy is a new field.
- amatus 11y ago
  Sorry, I only know some XRF, I don't know metallurgy.
- rsfern 11y ago
  It seems there's been a bit of research into Aluminum Tungsten systems[1]. The alloy systems described in the abstract are strengthened by particle formation (also called precipitation hardening), which is the primary strengthening mechanism used in most Al alloys[2]. In general, alloy design is an extremely high dimensional problem. You have composition, the forming processes, and heat treatments which all can profoundly affect the properties of the finished product. It's only since the fifties or so that we've really started to understand the internal structures of metals and how they affect properties like strength, and there are many open questions yet. [1] http://link.springer.com/article/10.1007%2Fs11661-008-9593-3 http://link.springer.com/article/10.1007%2Fs11661-008-9593-3 [2] https://en.m.wikipedia.org/wiki/Precipitation_hardening https://en.m.wikipedia.org/wiki/Precipitation_hardening
- bigger_cheese 11y ago
  I'm a materials engineer I graduated in 2010 back when I was at uni very little of the curriculum was dedicated to non-ferrous metallurgy. We probably spent as much time studying ferrous alloys as we did on Aluminium, Titanium, Copper and Nickel combined. That said I suspect the reason is likely patent related. Metallurgy is not a new field but Aluminium alloying is relatively new wasn't really until after WW2. Alot of industrial research tends to be locked away behind patents.
- racecar789 11y ago
  Heat treatment is a dark art. What works for one heat treater may not work for the other. Also, heat treaters are somewhat reluctant to share their secret sauce with customers. General hardening is no problem. The challenge is when a company needs a very specific hardness. There is a fair amount of trial and error with the heat treater (at least at first) before they get it right.
arcadi_tepes 11y ago
Its also interesting the on-device readout for the new alloy does not show a tungsten peak. https://www.youtube.com/watch?v=ChUsy8gWwvo&feature=youtu.be&t=241 https://www.youtube.com/watch?v=ChUsy8gWwvo&feature=youtu.be... The printout shows it, but is ~.08% off from 100%, which I assume is the Mg peak. But its a pretty big swing to go from no Tungsten to .106% Tungsten. I'm inclined to believe its a misread due to sandpaper or the coating (tungsten carbide coating on aluminum is very much a thing). I know metallography is expensive, but its weird to me to have such cool gizmo for XRF and to have a lab do such analysis and not do something simple like hardness testing. That is cheap and fast. Well, fast anyway. I can't comment on lab larbor costs. Instead of a lab, hitting up your local university materials lab for a grad student to do a quick hardness test and tensile testing would give very nice information and a basic guess as to type of material. XRD would also be more accurate than XRF I think, with proper preparation. Also, you would never test the cases as-is. The structural variable is small but important. A flat sample is better.

by amatus 11y ago

iaw 11y ago

Do you know if there's been experimentation with tungsten alloying of aluminum in the past? The thing that surprises me here is that if Apple did create an entirely new alloy with novel properties, why weren't those metallurgical characteristics already known? It's not like metallurgy is a new field.

amatus 11y ago
Sorry, I only know some XRF, I don't know metallurgy.
rsfern 11y ago
It seems there's been a bit of research into Aluminum Tungsten systems[1]. The alloy systems described in the abstract are strengthened by particle formation (also called precipitation hardening), which is the primary strengthening mechanism used in most Al alloys[2]. In general, alloy design is an extremely high dimensional problem. You have composition, the forming processes, and heat treatments which all can profoundly affect the properties of the finished product. It's only since the fifties or so that we've really started to understand the internal structures of metals and how they affect properties like strength, and there are many open questions yet. [1] http://link.springer.com/article/10.1007%2Fs11661-008-9593-3 http://link.springer.com/article/10.1007%2Fs11661-008-9593-3 [2] https://en.m.wikipedia.org/wiki/Precipitation_hardening https://en.m.wikipedia.org/wiki/Precipitation_hardening
bigger_cheese 11y ago
I'm a materials engineer I graduated in 2010 back when I was at uni very little of the curriculum was dedicated to non-ferrous metallurgy. We probably spent as much time studying ferrous alloys as we did on Aluminium, Titanium, Copper and Nickel combined. That said I suspect the reason is likely patent related. Metallurgy is not a new field but Aluminium alloying is relatively new wasn't really until after WW2. Alot of industrial research tends to be locked away behind patents.
racecar789 11y ago
Heat treatment is a dark art. What works for one heat treater may not work for the other. Also, heat treaters are somewhat reluctant to share their secret sauce with customers. General hardening is no problem. The challenge is when a company needs a very specific hardness. There is a fair amount of trial and error with the heat treater (at least at first) before they get it right.

arcadi_tepes 11y ago

Its also interesting the on-device readout for the new alloy does not show a tungsten peak. https://www.youtube.com/watch?v=ChUsy8gWwvo&feature=youtu.be&t=241 https://www.youtube.com/watch?v=ChUsy8gWwvo&feature=youtu.be... The printout shows it, but is ~.08% off from 100%, which I assume is the Mg peak. But its a pretty big swing to go from no Tungsten to .106% Tungsten. I'm inclined to believe its a misread due to sandpaper or the coating (tungsten carbide coating on aluminum is very much a thing). I know metallography is expensive, but its weird to me to have such cool gizmo for XRF and to have a lab do such analysis and not do something simple like hardness testing. That is cheap and fast. Well, fast anyway. I can't comment on lab larbor costs. Instead of a lab, hitting up your local university materials lab for a grad student to do a quick hardness test and tensile testing would give very nice information and a basic guess as to type of material. XRD would also be more accurate than XRF I think, with proper preparation. Also, you would never test the cases as-is. The structural variable is small but important. A flat sample is better.