TC beyond Ni200: Nickel Purity, Dicodes; Ti, SS, Resistherm NiFe30; Coefficient of Resistance
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OK so we can guarantee that any NiFe 70/30 or similar must be magnetic? Because of the ~ 30% Iron?
I might have lost track of the precise chemistry you thought you were ordering. It depends on the details of crystal structure that results. The stainless steels in the 300 series are not magnetic. The NiFe's we've been searching out are magnetic.
Duane
All I thought I knew/thought I was ordering was "Ni70Fe30". This is the same general description as Kanthal NiFethal 70 and Resistherm NiFe30. The key points being approx 70% Nickel and approx 30% Iron.
Of the two NiFes I have, both are magnetic, both have high TCRs (0.0032 and 0.005), both have much lower resistance than this wire. (And there's a third, not yet in hand, Stealth's NiFe70 which is also low resistance/high TCR; unknown as to its magneticity.)
But I know that small changes in alloys can seem to make big differences in metal, so I wasn't sure if we could be certain that non-metallic = not Ni70Fe30? I guess you're saying we can't be sure, except it doesn't match the other alloys we do have?
i'm writing an email to them now, would be great to have as many points as possible to include as to why this does not seem to be anything like what we expected.
As it's Crazy Wire, we sadly can't rule out out and out fraud. But I would assume it's more likely a mistake, or perhaps that there really is a "Ni70Fe30" alloy which matches these properties - no good for us, but not fraud/mistake?
Of the two NiFes I have, both are magnetic, both have high TCRs (0.0032 and 0.005), both have much lower resistance than this wire. (And there's a third, not yet in hand, Stealth's NiFe70 which is also low resistance/high TCR; unknown as to its magneticity.)
But I know that small changes in alloys can seem to make big differences in metal, so I wasn't sure if we could be certain that non-metallic = not Ni70Fe30? I guess you're saying we can't be sure, except it doesn't match the other alloys we do have?
i'm writing an email to them now, would be great to have as many points as possible to include as to why this does not seem to be anything like what we expected.
As it's Crazy Wire, we sadly can't rule out out and out fraud. But I would assume it's more likely a mistake, or perhaps that there really is a "Ni70Fe30" alloy which matches these properties - no good for us, but not fraud/mistake?
If it hasn't yet shipped then yes that is all I could currently recommend, sorry
I will try and get more to the bottom of it, but if you have a chance to cancel then that has to be the recommendation at this stage. Apart from anything else, I don't see how the TCR can be different from what I am seeing from resistance - or rather, it can't be better, only worse (if for example I heated to much more than 700°C)
Apropos of nothing, but my 35' of Unkamen 26awg Ti arrived today. Easy enough to work with, vapes as expected, but mine does have quite a lot of graphite on it, enough that a dry paper towel lightly ran down a length of it comes off with a pretty heavy gray line. No big deal, I pretty much always IPA wipe my wire before coiling, but don't assume Unkamen is always "clean".
Succinct and to the point as always Mr Craig - not to mention that I just tested Ni200 @ 99.6% Nickel, and that's also magnetic
So if approximately 100% of NiFe's components is magnetic, then yeah, I think we should be able to expect NiFe to be magnetic..
(Unless Ni200 is magnetic because of the 0.4% Iron, but then again that would surely just bolster the point about the 30% of Iron we know NiFe should have..!)
Edit: no, nickel is magnetic too on its own..
If you have enough wire length and a digital scale you could weigh it and compare against spec.
Just, thought I'd throw that in for good measure
Wasn't there some confusion about the terminology of the 70-30 NiFe's? If the nickel is really 70% the material well could be non-magnetic. Is that very high nickel material really what you wanted to order?
Duane
It depends on the crystal structure of the alloy. If it's austenitic (face centered cubic) it's non-magnetic. If it's ferritic (body centered cubic) it's magnetic. Both iron and nickel are magnetic but the alloys can result in either crystal structure depending on the other elements present. The 300 ss and the like are non-magnetic because they have an austenitic crystal structure. I don't know what other alloying elements there could be in the material they supplied to you but other elements can cause the crystal structure to change from one form to the other.
Duane
Duane
Ni70 Fe30 is what we're expecting. The confusion was that it's sometimes called NiFe70, sometimes NiFe30. But in both cases, it's approx 70% Nickel, 30% Iron, with usually some trace elements in there as well. Sometimes it lists the Nickel as 70%, Iron as 'balance', sometimes the other way around.
Examples:
The first is called "NiFe70", the latter "NiFe30", and this is the confusion in naming - but both are approx 70% Nickel and approx 30% Iron.
In the case of Crazy, they seem to try to avoid confusion -they say "NiFe30 wire (Ni70Fe30)", ie giving it its more common name NiFe30 (as Dicodes/Isabellenhütte call Resistherm) then clarifying that it's Ni70 Fe30.
Yes nickel sure is magnetic, I'll just read, well
The element Nickel (Ni) is one of the few ferromagnetic metals. Ferromagnetic means they are attracted to magnets and can be magnetized themselves. Most metals aren't magnetic with the exception of iron, nickel, cobalt, gadolinium, neodymium and samarium
OK so we cannot absolutely assume that any given Ni70 Fe30 alloy should be magnetic, just because the other ones we've looked at are, and just because it's 99.9% made up of magnetic Iron and magnetic Nickel?
I ask because I need to know if I can legitimately include "it's not magnetic" in the email to them calling it out..
I would just ask the for the detailed chemistry. They could be supplying a chemistry that makes the material different from what you were expecting. It could be an honest (on their part) misunderstanding of the materials we were expecting.
Duane
It's not as simple as that. As druckle said, it depends on the atomic structure. A materials science professor at UC Berkeley explains here.
Basically the metal composition of the alloy isn't the only thing that matters. Deformation or bending of the metal can cause it to gain magnetism when there was none previously. He uses the example of 304 SS. It is not magnetic at room temperature but can gain a slight magnetism when bent or deformed.
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