The copper-aluminium alloys, known as aluminium bronzes, form an important group of engineering materials, characterized by their high strength and corrosion resistance. A solid solution containing up to 9.4+wt% Al with a narrow freezing range similar to the brasses forming a peritectic at 1037°C and 8.5wt% Al. Alloys containing less than 8% aluminium are single-phase a alloys. Solidification commences with the formation of a dendrites. The freezing range is short with the as-cast structure being essentially single phase. Segregation is not pronounced.
The alloy containing 10% aluminium solidifies as B depositing a as the line DR is crossed and at 565°C the remaining B decomposes to form lamellar eutectoid a +y2. The reaction is, of course, diffusion controlled, and normal casting rates result in the retention of B. The alloys we consider in continuous casting have lower aluminium contents forming an all-a structure.