Cu-40%Zn powder is milled at -30 ℃ and room temperature respectively with a high energy mill. The phase transformation and microstructure are observed under X-ray diffractometer and scanning electron microscopy. The mechanical alloying of Cu-40%Zn indicates diffusing of Cu into Zn to finally form Cu

0.64

Zn

0.36

and ZnO. The lattice distortion of the alloyed powder in low-temperature milling is stronger than that in room temperature milling. The grain size of the powder milled at low temperature is bigger than that at room temperature. The negative effect of cold welding can be depressed in low-temperature milling without adding process control agent. The Cu-Zn binary system belongs to ductile-ductile system in room temperature milling

but it manifests the characteristic of brittle-brittle system when milled at low temperature.