Effects of Nb Element on Mircostructure, Thermal Conductivity and Melting Point of Cu-Ni-Nb Alloy Prepared by Vacuum Arc-Melting
Effects of niobium element adding method and addition content on the microstructure, thermal conductivity and melting point of Cu-Ni-Nb alloys prepared by vacuum non-consumable arc-melting were studied. We found that it is difficult to dissolve high melting point element Nb into Cu-Ni alloy by one-step smelting. However, Nb can be dissolved into Cu-Ni alloy in style of Nb-Ni master alloy by two-steps smelting. New phases Ni3Nb and Ni8Nb generate in matrix of Cu-Ni alloy. In addition, the thermal conductivity coefficient of Cu-Ni-Nb alloy increases as increasing the content of Nb, while melting point of that alloy decreases as increasing the content of Nb. Moreover, the thermal conductivity coefficient of Cu-20Ni-3Nb alloy is 43.23W/m•k, while melting point of that alloy is 1146°C. That meets the requirement of pure copper casting process.