
Aluminum and strength - jessaustin
http://leancrew.com/all-this/2015/08/aluminum-and-strength/
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amatus
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.

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iaw
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.

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rsfern
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)

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brandon272
I couldn't find it in the quick digging I did; can anyone tell me where he got
the 6S case, which he describes as a case that is "likely" from the new 6S? I
assume it's either a technical reproduction based on rumour or an intentional
gift from Apple to build hype?

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kaolinite
During the initial production of a new iPhone, which seems to start a month or
two in advance of the release, parts are regularly smuggled out of the
factories - especially case backs. They're sold to case manufacturers mainly
who want the specs so they can design iPhone cases that are out on launch day.

~~~
brandon272
Interesting! Wouldn't that make him in possession of stolen material?

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digikata
Could it be an alloy designed by Liquidmetal?

[https://en.wikipedia.org/wiki/Liquidmetal](https://en.wikipedia.org/wiki/Liquidmetal)

~~~
amatus
Looks like the Liquidmetal alloys are zirconium-based, the XRF showed that it
was an aluminium-based alloy. So, no.

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iaw
This is pretty interesting because it raises the question about additional
applications of this and similar alloys in the future. I wonder what, if any,
material property drawbacks there are for the new alloy.

~~~
bigger_cheese
Usually in industrial design when you select a material you do so based off a
constraint selection process:
[https://en.wikipedia.org/wiki/Material_selection](https://en.wikipedia.org/wiki/Material_selection)

Typically you have material specific constraints (workability, cost, ease of
sourcing) and application constraints (for a phone case this would be weight,
stiffness, min/max dimensions things like that).

Once you have determined the constraints you can solve for the objective
function using numerical methods i.e. Solve all the simultaneous equations.

That will identify the materials which are most suited to the chosen
application. And will eliminate materials with drawbacks that cause them to
fail to meet the constraints (so you don't end up with a iphone case made from
diamond which costs a fortune or from ceramics which weigh a tonne).

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jessaustin
_...we can tell how cool Lew is from his backwards baseball cap._

Note to self: stop wearing caps that way _before_ beard starts turning white.

~~~
nostromo
Backwards hats go back to at least the mid-80s. By that regard, they should
now be a sign of middle-aged wisdom, not of youth.

~~~
sic1
this guy gets it, well said, sir. "darn kids and their forward hats"

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Animats
I have to laugh at Apple's efforts to toughen up their phones. I own a
Caterpillar brand phone, which will survive being run over by a truck.[1][2]
Drops on cement result in zero damage. When an Apple product can pass IP67
certification, then they can talk about ruggedness.

[1] [https://www.youtube.com/watch?v=mVPku-
xItv8](https://www.youtube.com/watch?v=mVPku-xItv8) [2]
[https://www.youtube.com/watch?v=sggbV7j_rLA](https://www.youtube.com/watch?v=sggbV7j_rLA)

