Where may I find a data about of density and specific heat of CuMn? I can't find any data about it.
Did you try Google Scholar? I did a search on "CuMn density specific heat" and found several hits, with this one being at the top of the list:
Search additionally on "copper manganese" + heat + capacity. Densities can be found in X-ray diffraction studies on copper-manganese alloys.
Separate names with a comma.