aging treatment the solid solution treatment cold forging and the aging treatment were conducted under the same conditions as example 1 the hot forging was conducted at a working ratio of 30 the material thus obtained showed a tensile strength brinell hardness and an electric conductivity of 34 0 kg mm 2 h b 114 and 30 iacs respectively at the normal temperature a metal mold of the same shape as that in example 1 was produced from this material and was subjected to 1000 cycles of casting of the melt of cast iron no run out nor fins not to mention cracking of the metal mold due to thermal stress was observed a material sample no 1 was prepared from an alloy consisting essentially of 0 05 wt of zirconium 0 12 wt of titanium 0 74 wt of chromium and the balance substantially copper by subjecting this alloy to a solid solution treatment and then to an aging treatment a material sample no 2 was prepared from the same alloy as sample no 1 by a process having the step of a cold forging between the solid solution treatment and the aging treatment a material sample no 3 was prepared from the same alloy as sample nos 1 and 2 in this case the material was subjected to a hot forging in advance to the solid solution treatment and to a cold forging before the aging treatment i e after the solid solution treatment in each case the solid solution treatment was conducted by heating the alloy at 1020 u00b0 c for 1 5 hours and.