The other metal is probably 420j steel, a flexible steel usually used in the liners of pocket knives.
I'm just guessing because the Shun series of knives made by KIA (The parent company of Kershaw and Shun and ZT) have kitchen knives which utilize a vg-10 core and 420j as the outside layers.
And just so you know, the proper term for this type of blade welding is called san mia, it is where a hard center steel has softer iron/low carbon steels welded to the outside of it to increase flexability of the blade while still keeping a high rockwell hardness on the cutting edge of the knife.
Here is a paragraph I directly copy and pasted from the Shun KAI website about one of their kitchen knives with this steel.
"Sora uses Shun's proprietary Composite Blade technology to bring together a VG10 san mai cutting edge with a Japanese 420J stainless steel upper. This technology puts high-performance material exactly where it's neededon the edge. The two blade sections are laser cut, then fit together like pieces of a jigsaw puzzle. Braze welding permanently joins them. The attractive wavy pattern at the joint is based on traditional Japanese sword hamon lines."