Pb-30 BI包晶合金定向凝固的两相微观组织研究.pdfVIP

学兔兔 May 2010 铸 造 Vo1．59 NO．5 FOUNDRY ·445· Pb一30％BI包晶合金定向凝固的两相微观组织研究 胡小武，李双明，高斯峰，刘 林，傅恒志 (西北工业大学凝固技术国家重点实验室，陕西西安710072) 摘要：对Pb．30％Bi包晶合金进行定向凝固试验，研究了在不同生长速率、不同试样直径条件下获得的两相微观组织， 并对其组织的形成及微观组织尺度进行分析。试验结果表明，当生长速率V由1 I~m／s逐渐增大到100lurds时，微观组织 经历胞状初生 相+胞问包晶p相到枝晶状 相+枝晶间p相微观组织的转变。当生长速率V≤0．5 tzrrds时，在小直径 (1．8mm)试样中发现不完全带状组织，而在大直径 (7mm)试样中却得到了振荡组织。同时发现，初生d相的一次枝 晶间距A与凝固速率 之间存在AV 6=-241．0 m 6S 的关系，这与Hunt模型和Trivedi模型较好地吻合。 关键词：Pb．30％Bi包晶合金；微观组织演化；定向凝固；一次枝晶间距 中图分类号：TGI 14．4 文献标识码：A 文章编号：1001—4977(2010)05—0445～05 Investigation of Two··Phase Microstructure During Directional Solidification of Pb--30wt％Bi Peritectic Alloy HU Xiao—WU，LI Shuang—ming，GAO Si—feng，LIU Lin，FU Heng—zhi (State Key Laboratory of solidification Processing，Northwestern Polytechnical University， Xi’an 71 0072，Shaanxi，China) Abstract：DirectionaI solidification experiments were conducted on Pb．30 ％Bi peritectic alloy to investigate the two—phase microstructure at various growth rates and diameters of samples，and the formation of two—phase micrOstructure and the micro—scale were also studied．The experiment results show that the transition of the structure from cellular primary o(phase and inter．cellular peritectic 13 phase to dendritic primary a phase and inter-dendritic peritectic 13 phase was presented with increasing the grOwth velocity fr0m 1 iJm／s to 1 00 pm／s．Whereas the incomplete banded structure and the oscillatory structure were observed jn sample with diameter of 1．8 mm and 7 mm as the growth rate V≤0．5 om／s．respectively．It iS also demonstrated that the primary dendrite arm spacing of a phase coincides with the equa