Aluminium, copper and stainless steel are all classified as A1 by the EU (source 1). Be aware that the classification does not apply if the material is in powdered form.
Class A1 is defined as “no contribution to fire”. This means that materials in Class A1 do not have to be tested on their own for their reaction to fire – they are defined as non-combustible.
The standard EN 13501-1 states that the classification in source 1 applies in this standard (p. 6). This means that the standard accepts materials in Class A1 without further testing for their reaction to fire:
”Class A1 and A1L products will not contribute in any stage of the fire including the fully developed fire. For that reason they are assumed to be capable of satisfying automatically all requirements of all lower classes.” (p. 44)