can tin plate be used as enclosure material at high freq - about 10GHz?

I want to ask, what would be effects of magnetism? Can tin plate enclosure box be used at such high frequencies? Why aluminium is always used, is it cost and thermal stability problem, or there is also magnetism impact... For example, if we use DRO oscillator, can it be done using tin plate enclosure?

Yes, you can use tinned steel as a shield material. Aluminum is preferred as it is harder and resists corrosion better. What magnetism are you talking about?

Thank you for reply! why i ask this, I saw small magnet inside aluminium cnc circulator. So it stayed in my mind.. and i imagine how enclosure influences somehow whats inside the box.

Ferrite circulators have magnetic circuits sensitive to ferromagnetic objects. Typical circulator carries a label "no steel or iron closer than six inches away" including screws. So keep this in mind if you intend to use a tinned steel case.

brass, aluminum, nickel, steel, stainless steel, copper...all can be used. Non conductive materials, like plastic, need to be metal plated/covered to work. The cover to body contact resistance will be important for shielding effectiveness, so a metal coating that does not corrode is preferred. Tin IS a good one in that tin oxide is conductive. Aluminum is actually a poor one, since aluminum oxide is an insulator...hence the reason a lot of people plate or chemically convert the aluminum surface to maintain conductivity.