【摘要】 对Cu-7.9%Co包晶合金不同定向凝固速率下的凝固组织进行了研究。结果表明:在定向凝固速率1μm/s~100μm/s下,随凝固速率的提高,初生α-Co相体积分数减少,使形态从定向生长的枝晶转变为等轴枝晶,相应地β-Cu包晶相的生长界面形态由平界面转变为枝状界面。利用最高界面生长温度假设,计算得到了凝固速率在0.55μm/s~5000μm/s范围内α-Co相领先于β-Cu相生长,与实验结果较为吻合;并当凝固速率大于5000μm/s时,β-Cu相的凝固界面生长温度高于α-Co而成为领先相,可以不通过包晶反应直接从熔体中凝固析出。更多还原

【Abstract】 Directionally solidified microstructures of Cu-7.9%Co peritectic alloy have bee investigated at the growth rate ranging from 1 μm/s to 100 μm/s. The results show that the morphology of α-Co primary phase changes from a columnar dendrite to an equiaxed dendrite and its volume fraction decreases with increasing of growth rate. Simultaneously, the interface morphology of β-Cu peritectic phase becomes unstable from planar to dendritic interface. The theoretical analysis results indicate that α-Co phase can grow ahead of β-Cu phase as the growth rate ranges from 0.55 μm/s to 5000 μm/s, which is in agreement with the experimental results. In addition, when the growth rate is more than 5000 μm/s, β-Cu phase can grow as the primary phase and directly solidifies from the liquid metal without peritectic reaction..更多还原