玻璃净化剂组分对Cu_(50)Ni_(50)合金熔体过冷度稳定性的影响

Effect of glass composition on undercooling stability of Cu_(50)Ni_(50) alloy melts

在高真空下 ,研究了净化剂B2 O3,79%SiO2 + 1 2 .5%B2 O3+ 2 .2 %Al2 O3+ 0 .6%CaO + 5.7%Na2 O(简写为Na Ca Al B Si)和 50 %Na Ca Al B Si+ 50 %Na2 B7O4对Cu50 Ni50 合金熔体在循环过热过程中的过冷度及其稳定性的影响。结果表明 ,B2 O3的净化过程为纯物理净化 ,合金熔体在循环过热过程中不能获得稳定的深过冷 ;Na Ca Al B Si玻璃的净化过程为物理 -化学复合净化 ,但由于该净化剂粘度大 ,在循环过热的冷却过程中因发生合金熔体与净化剂分离 ,使合金熔体表面氧化 ,导致合金熔体同样不能获得稳定深过冷 ;50 %Na Ca Al B Si+ 50 %Na2 B7O4玻璃的净化过程为物理 -化学复合净化 ,该净化剂粘度适中 ,合金熔体在循环过热过程中可以获得稳定深过冷。

The undercooling and its stability of Cu 50 Ni 50 alloy melts were investigated in vacuo using different glass slags, B 2O 3, 79% SiO 2+12.5 B 2O 3+2.2% Al 2O 3+0.6% CaO+5.7% Na 2O(simplified as Na Ca Al B Si), and 50% Na Ca Al B Si+50% Na 2B 7O 4. The results showed that different glass slag has different denucleating mechanism. The purification of B 2O 3 glass is only a physical process. The alloy melts can not obtain stable undercooling during superheating cooling cycle. Taking 79% SiO 2+12.5% B 2O 3+ 2.2% Al 2O 3+0.6% CaO+5.7% Na 2O as purifying agent, the denucleating mechanism is a comprehensively physicochemical process. Yet the stability of undercooling is still low because of the separation between melt and glass occurred during cooling process of superheating cooling cycle. Stable undercooling can be obtained by physicochemical denucleating processes of 50% Na Ca Al B Si+50% Na 2B 7O 4 molten glass because of its appropriate viscosity.