I have a nice block of “titanium” but don know if it is an alloy. The likeliest alloy would include 6% aluminum and 4% vanadium, I think. Easy ways to tell?
Spark test?
Can you get a couple of drops of hydrofluoric acid and concentrated nitric acid?
I expect titanium would give brilliant white sparks, but how do the other elements change that if they’re there? Aluminum by itself doesn’t spark but I have no idea of vanadium, nor of how combinations of elements compare to their pure behaviors.
Your best and most conclusive test would be a chemical analysis. You could perform a hardness test, as most commercially pure titanium grades are much softer than the alloys, but you could have some annealed alloy.
My question would be, why do you care? Does it make any difference?
I’m a machinist and have handled literally thousands of pounds of Ti.
I worked for a company that made bone screws, pins and rods for implants.
Titanium is used for it’s weight to strength radio and because it is inert. The best “medical grade” was 94 percent pure. Sorry my only cite is my memory of filing hundreds of certifications, I don’t work there anymore.
Toured a rolling mill where they made Ti. bars and wire. Best recollection talking about what they used for bicycles and golf clubs I was told the alloy could be as little as 50 percent.
Cost wise is a huge difference.
Any marks on the block? How big is it? Where did you get it? I could speculate better.
Burn some shavings, then mix with distilled water. Vanadium oxide is water soluble, forming a yellow coloured solution.
Pure titanium is 4.506 g·cm−3 at room temperature. If you have a scale, some water, and a graduated cylinder, you should be able to see how close your sample is to that.
I was going to suggest an Archimedes density check, but I figured that would only possibly confirm that it is or is not pure Ti. Also, I guess it’s possible for some alloys to be similar densities to the pure metal, so maybe not even that.
Here’s a table of densities of common metals Density - Wikipedia
Offhand it looks like there’s not much that’s close to Ti. So unless your sample was unlucky enough to be a mix of both lighter and heavier alloying elements you’ll at least get a close WAG from the density test.
ETA: don’t have time to run the calc before the edit expires, but 6% Al & 4% V ought to be lighter than pure Ti by a detectable amount.
Take it down to a metals recycling place? One that deals in expensive scrap should have a handheld spectrograph analyzer.
Thank you Mr. Goob.
What I have is a rectangular block that appears to have been cut from a 2" plate, because there are opposite faces that look like a rolled mill finish, quite flat and fairly smooth but with fine texture like I see on some other nonferrous rolled plate. Two other opposite faces appear sawn and are about 1.5" apart. One of the remaining faces appears torch cut with a characteristic sculpted or windswept looking texture like sand or snow gets, plus some blueish discoloration that spills slightly from its edges onto the other faces. The last face has a mixed look, partly sawn and partly ground, that I can’t figure out. The torch and mixed faces are about 2" apart. (the dimensions are from memory, I don’t have the block here this morning, and I can get good measurements if it helps)
This was a gift from a machinist friend with a lot of experience, who retires this month. I collect elements and he’s given me a few things he’s collected over the years, as he is trying to save less and less stuff these days. He gave me a wee bit of platinum wire recently, and we had a great time looking at a small blob of osmium recently; if I get over my worries we’ll probably play with a small and as yet still wrapped chunk of beryllium, and may try rubbing together pieces of indium and gallium to see if we can really alloy them into liquid eutectic without melting them.
But he had this titanium chunk for a long time and does not know if it’s pure or an alloy. I should ask him more about its origin but I have the sense he thought it was neat and maybe rescued it from the trash or otherwise snagged it without knowing much about it. I don’t think he ever was involved in making implantable parts. I think it’s more likely it was being used for chemical resistance, which I understand from the web favors the choice of pure Ti (grades 2, 4 and 7).
Thanks!
Thanks to all who suggested density measurements. Looking at manufacturer and supplier web sites I find that pure Ti and the common 6Al-4V alloy are both 4,790 kg/m^3. This isn’t surprising, as aluminum is less dense than Ti while vanadium is more dense, though the ways the atoms can fit together in crystals and their amorphous boundaries enters into it too.
From what you said about using it for chemical resistance, If I had to bet it’s a hunk of 6Al 4V.
Sounds like it’s a raw edge of the end/side of the plate from the hot rolling process. And yes it “blues” easy from the heat of the bandsaw.
If you want to machine it, set up as if Al. It’s very gummy like Al is gummy compared to steel. Up your RPM slow down the feed and take very shallow depths of cut. Coolant if you can.
Use a handheld XRF analyzer. Nondestructive and quick.