Prior to 9.0.1, aluminum plates could be used to craft several items.
Aluminum plates used to be part of the crafting recipes below. Aluminum Plates have been replaced with Aluminum ingots in every crafting recipe (Click me for all recipes).
Prior to 9.0.0, aluminum plates crafting involved placing an aluminium ingot on an anvil and a hammer could then be used on it. Pictured below are the four stages of an aluminium ingot being hammered into an aluminium plate on an anvil.