I searched the interwebz, came up with nothing, so I called the manufacturer. Got a tech rep that definitely knew her stuff. I hope I can explain it well enough. It doesn't simply mean resistant to flowing.

My guess: it isn’t eutectic.

eutectic: “relating to or denoting a mixture of substances (in fixed proportions) that melts and solidifies at a single temperature that is lower than the melting points of the separate constituents or of any other mixture of them.”

With a non-eutictic alloy near the melting point some portions of it will remain solid, hence sluggish, while others portions are liquified.

https://www.researchgate.net/f...solid_fig7_279814785

This came to mind:

quote:

Originally posted by Pipe Smoker:
My guess: it isn’t eutectic.

eutectic: “relating to or denoting a mixture of substances (in fixed proportions) that melts and solidifies at a single temperature that is lower than the melting points of the separate constituents or of any other mixture of them.”

With a non-eutictic alloy near the melting point some portions of it will remain solid, hence sluggish, while others portions are liquified.

https://www.researchgate.net/f...solid_fig7_279814785

I think you have explained it as well as she did, but different. She said the liquidus and solidus have wide range, in this case liquidus 1370F, solidus 1225F. She said this makes this solder (Silvaloy 450) better able too fill large gaps, but also makes it harder to work with. It needs to be heated quickly as it starts to melt, as bringing it slowly to fully melted once it starts to melt can separate out some of the elements.

How do you know this? Are you a metallurgist?

Here is a good description on the manufacturers website: https://blog.lucasmilhaupt.com...n%20brazing%20joints.

quote:

Originally posted by pbslinger:
<snip>
How do you know this? Are you a metallurgist?

No, just an engineer that knows lots of mostly useless technical stuff. I have a BSEE, but spent my entire career designing digital logic for supercomputers (1st half of career), then mobile phones (2nd half of career). Used almost none of my EE schooling.

I also know that “pbslinger” is “lead slinger”.
And good on you for that!

BTW – For most electronic and electrical work eutectic tin/lead solder is the best choice. Tin 63% / lead 37%. Sometimes stated as 60/40.

quote:

Originally posted by Pipe Smoker:
BTW – For most electronic and electrical work eutectic tin/lead solder is the best choice. Tin 63% / lead 37%. Sometimes stated as 60/40.

Do you know what solder is best for general shop use, strong and easy tinning and flowing? I need to solder a couple of brass oil coolers for marine transmissions. They are brass.

quote:

Originally posted by pbslinger:

quote:

Originally posted by Pipe Smoker:
BTW – For most electronic and electrical work eutectic tin/lead solder is the best choice. Tin 63% / lead 37%. Sometimes stated as 60/40.

Do you know what solder is best for general shop use, strong and easy tinning and flowing? I need to solder a couple of brass oil coolers for marine transmissions. They are brass.

This would depend on the use.

For avionics, 60/40 is used due to its flexibility when solid.

For consumer electronics, non-lead is used be of the whole, "lead is bad, let's go green" movement. This is partly why consumer electronics are more fragile.

For plumbing (like potable water), silver solder is preferred but typically used where the outside meets the inside (something about temp differentials but, I am electronics, not a plumber).

If you are in high-temp environment (over 750 degrees F, 60/40 will fail quickly due to its lower flow temp.

With all that, sounds like 60/40 might work for your application though however - YMMV