For the first time, Cu(AlTi)-alloy active-electrode coupled with RuTa inert-electrode is proposed to improve the reliability of nonvolatile Cu atom switch. The remarkably high rupture temperature (Tr >400oC) of the nanometer-scale Cu bridge with the high thermal resistance (Rth) is realized by the Cu-alloy without increasing programming current. The anti-Cu diffusive, RuTa-alloy improves the retention of the ON-state at 150oC and endurance to >104 cycles. The metallurgical prescription is a key to improve the reliability and switching performance of the conducting bridge.