Regarding aluminum plates, in addition to its common characteristics such as lightness, corrosion resistance, and easy processing, here are some lesser-known "cold knowledge":

"Torn" aluminum plates: If pure aluminum plates (especially high-purity aluminum) are made very thin (such as thin foils in certain alloys or states), they can be "torn" in theory by applying tension in a specific direction, just like tearing paper. This is because the aluminum crystal structure is relatively easy to cleave (separate along the crystal plane) under a specific orientation. Of course, it is impossible to tear aluminum plates of ordinary thickness by hand.

"Cold welding" in space: In an ultra-high vacuum space environment (such as inside a satellite), if two very clean and flat aluminum plates are in close contact, they may be directly "bonded" together at room temperature, resulting in cold welding. This is because in a vacuum, there is no oxide film blocking the surface of the aluminum plate, and the attraction between metal atoms directly acts, causing the two metals to spontaneously fuse. In the Earth's atmosphere, a dense aluminum oxide protective film will instantly form on the aluminum surface, preventing this phenomenon.

Once the "Emperor's Metal" More Precious Than Gold: Before the mid-19th century, aluminum was extremely difficult and expensive to refine. Napoleon III used aluminum tableware to entertain his most distinguished guests, while lesser guests had to use gold tableware. At the time, aluminum was much more valuable than gold. It was not until the invention of electrolysis (1886) that aluminum became cheap and aluminum sheets became widely used.