It's a two part question. First I need to know if a non-eutectic alloy exists (or can exist) that melts in the range listed and then a vendor experienced with such a material.
NickE,
Bi-Sn has a eutectic at 46 at% Bi (~60 wt%) composition & 138.5C; the liquidus at 58 wt% Bi is ~10F higher.
Probably all common solder alloy systems have eutectics. 45Bi-23Pb-19In-5Cd-8Sn maybe melt at a quinternary eutectic, but my books don't go that far!
cbert,
Does "non-eutectic alloy" mean a composition a bit away from the eutectic in order to give a 10F melting range? I.e., either a hypo- or hypereutectic alloy with a liquidus at 230F & a solidus (or eutectic) at 220F. Preferable to say 'off-eutectic.'
Giving a melting range makes it redundant to say 'non-eutectic;' a eutectic defines a single temperature.
[If looking for a alloy system w/o any eutectic (like Cu-Ni), probably SOL.]
Search for "solder melting range" & low-temperature “fusible alloys,” then look at temperatures. e.g., Alloy 16 in the 'Table of Specialty Alloys and Solders,' of composition 44.7Bi-22.6Pb-16.1In-11.3Sn-5Cd, has a liquidus at 126F & solidus at 119F.
For application, first Ni-plate the steel tube to improve solderability (not Cu, it may build up in the liquid metal & change the melting range). Then apply by soldering (for a small quantity) or hot-dip (large quantity) technique. Maybe necessary to have a surface layer of flux atop the liquid metal bath owing to easy oxidizability of In. Can also find a non-In-containing alloy.
kenvlach- I was trying to ge the poster to provide more information. The alloy's I mentioned were just pulled out of the Guide to Engineered Materials that sits on my desk. I didn't realize this was a solder alloy question, but then again that makes sense.
To do an alloy designe like this wouldnt it be effective to search for an alloy system that has a eutectic around the min melting point needed. Then shift the composition either way about the eutectic composition to increase the liquidus to the max melting temp required?
cbert,
can you tell us more about the non-eutectic requirement?
NickE,
I don't think there's necessarily a difference between solder alloys & low temp fusible alloys except for application. Solders are tailored for wettability and some for electronic applications.
Thanks to all of you for your detailed replies. I've received more info on the requirement from our customer. Heavy metals cannot be a part of the composition. I had previously said that the material must "melt" between 220F and 230F. A better description of what's truely needed is a metal that will weaken in the temperature range so that it fails catostrophically thus releasing pressurized gas. I've got a 10 foot hollow steel tube, 1/8" to 1/4" in diameter that's pressurized to about 100 psi. I need to release the gas charge in the event of a fire. I was envisioning small holes, approx. .020 in. diameter, drilled every 6 inches. One idea was to coat the tube with a low melt-temp material which would cover the .020 holes. Another idea was to have small "plugs" spaced every 6 inches. Any ideas?
