Work describes research results of a structure, joining dissimilar materials, obtained with electron-beam welding. Temperature quality of the welding area was evaluated with mathematical simulation. Aluminum and copper steels were welded together. Weld and near-weld area chemical and structural compositions were observed with modern metallographic methods and scanning electron microscopy technic. Main patterns of metall microstructure formation in weld zone were established. Chemical component distribution in a weld area was analyzed.