The invention relates to the field of
copper-
nickel (CuNi)
alloy corrosion resistance improvement using rare-earth modification and
grain boundary engineering, in particular to a preparation method ofyttrium-based heavy-rare-earth
copper-
nickel alloy. The
yttrium-based heavy-rare-earth
copper-
nickel alloy comprises, by
mass percentage, 9-12% of Ni, 1.0-2.0% of Fe, 0.5-1.5% of Mn, less than 0.01%of S, less than 0.01% of P, less than 0.01% of C, 50-300ppm of Y, less than 0.1% of other impurities and the balance copper. The alloy is prepared by
smelting the raw materials into
casting blanks under vacuum
gas protection and subjecting the
casting blanks to
forging, hot rolling, primary cold rolling, intermediate annealing, secondary cold rolling and finished-product annealing. The high-
corrosion-resistant CuNi alloy structurally comprises an alpha-Cu matrix and
yttrium-based rare-earth compound inclusion, the grain size (not considering twin crystals) of the matrix is 40-60 micrometers, the low-energy
coincidence site lattice
grain boundary proportion of the matrix is larger than 75%, and the ratio of maximum free
grain boundary length to free grain boundary total length is smaller than 0.3. The CuNi alloy is low in preparation cost, applicable to board and band products, excellent in
corrosion resistance and especially applicable to service environments high in
seawater corrosionresistance requirements, and the preparation method of the CuNi alloy is simple in process and easy to operate.