The invention provides a fine-grained
zinc-based
alloy for a die and a preparation process thereof. The invention is characterized in that the fine-grained
zinc-based
alloy for the die is composed of a matrix
alloy, intermediate alloys, an alterant and a
scouring agent and comprises 12.5 to 16.5% of Al, 8 to 12.5% of Cu, 0.01 to 0.05% of Mg, 0.10 to 0.25% of Ti, 0.01 to 0.03% of B, 0.3 to 0.7% of Zr, 1 to 3% of Si, 0.4 to 0.8% of Mn, 0.2 to 0.8% of Re and 0.4 to 0.5% of ZnCl2, with the balance being Zn, wherein Re comprises, by
mass, 45 to 55% of Ce, 10 to 20% of La, 7 to 15% of Y and 4 to 10% of Gd. The preparation process comprises the following steps: fusing the alloys in a
crucible resistance furnace or a medium-frequency induction
melting furnace; preparing a semi-
solid zinc-based alloy through
electromagnetic stirring; carrying out
casting after temperature drops to 550 DEG C; and carrying out
water cooling or
air cooling. Compared with the prior art, the invention has the following advantages: the fine-grained zinc-based alloy for the die has the following mechanical properties at normal temperature, i.e., sigma b of 492.6 MPa,
delta s of 1.42% and HBR of 168; even at a high temperature of 200 DEG C, sigma b reaches 216 MPa and
delta s reaches 26%, completely according with the requirement of a common injection die for the
mechanical property sigma b of 120 to 150 MPa at the temperature of 200 DEG C.