Cu-15Ni-8Sn-0.4Si合金铸态组织结构及成分偏析研究

The Study of Cast Structure and Component Segregation in Cu-15Ni-8Sn-0.4Si Alloy

用金相、扫描电镜及电子能谱微区成分分析等方法对添加少量Si的Cu 15Ni 8Sn合金的铸态组织结构及成分偏析进行了研究。结果发现 :Cu 15Ni 8Sn 0 .4Si合金的铸态组织分为三层 ,除具有明显的枝晶外 ,还有块状的 (Cu、Ni) 3Sn相和溶有少量Cu的Ni2 Si和Ni3Sn相组成的第二层 ,在两层之间为组织形态复杂的过渡区。宏观上铸态组织存在Sn的反偏析 ,Sn的含量从外到内呈现下降趋势。与非真空熔铸相比真空熔铸能明显改善Cu 15Ni 8Sn 0 .4Si合金反偏析现象。均匀化退火对改善Sn的反偏析作用不大 ;枝晶组织可基本消除 ,但Ni、Si元素形成的化合物仍难以完全溶解。添加少量Si的Cu 15Ni 8Sn合金由于Ni2 Si和Ni3Si相的形成 ,通过阻碍晶粒长大和时效沉淀而强化合金。

The cast structure and component segregation were studied in Cu 15Ni 8Sn with addition of Si by optical microscope, SEM and energy spectrum analysis. It is found that in the alloy the cast structure has three layers. Besides apparent treelike crystals, there exist massive (Cu?Ni) 3Sn phase ?Ni 2Si and Ni 3Si phases containing a little Cu. These phases compose the second layer. Between two layers, it is the complex structural transitional zone. There exists Sn negative segregation in the cast structure by macro observation and the content of Sn decreases from outside to inside. The improvement of negative segregation in the alloy by vacuum smelting is more apparent than by atmospheric smelting. But the action of homogenized annealing is not apparent very much for the condition. Treelike crystals are eliminated approximately .On the contrary, the compound constituted by Ni and Sn element is'nt still solved completely. It is estimated that Cu 15Ni 8Sn with Si will be strengthened because of the formation of Ni 2Si and Ni 3Si new phases by the means of rejecting the grain growing and aging deposition.