the operation of joining two or more parts together by molten metal is called
Metalworking Welding is a fabrication process that joins materials, usually metals or thermoplastics, by causing coalescence. This is often done by melting the workpieces and adding a filler material to form a pool of molten material that cools to become a strong joint, but sometimes pressure is used in conjunction with heat, or by itself, to produce the weld.
Partial melting Partial melting is an important consideration in geology with respect to the chemical differentiation of crustal rocks. Virtually all rocks on Earth derive from material from the interior of the earth that has been partially melted. The main places where partial melting occurs are subduction zones, mid-ocean ridges and hotspots. In all these places partial melting is often associated with volcanism, although some melts do not make it to the surface. Partial melts are thought to play an important role in enriching old parts of the continental lithosphere in incompatible elements.[1] Partial melts produced at depth move upwards due to the compaction of the surrounding matrix.[2]