'A Snowball’s Chance in Hell' - Unimpossible Missions - GE

Admittedly, dunking a snowball in molten metal does seem a little stupid, but if's striking when that snowball doesn't appear to have melted even a little bit after its dip.

Sadly there's no info as to what the ultra-alloy is (other than that it's 'nickel-based'). On the IFLScience article about the video, we learn that the metal can is "just over 3 millimeters (0.11 inches) thick, then lined with 5 centimeters (2 inches) of fibrous alumina-silicate insulation."

There's some more information on GE's website where they highlight this and other parts of their Unimpossible Missions program.