摘要
在1480～1510℃对Ti-48A1-2Cr-2Nb合金分别进行了0、10、15、20次循环处理，研究了该合金凝固组织的演变规律。结果表明，未处理的合金组织由粗大的片层团组成；随着循环处理次数的增加，Ti-48A1-2Cr-2Nb合金由粗大的片层团向细小的等轴晶转变，且分布更加均匀。分析表明，在循环处理的快速加热阶段，初生晶粒发生了重熔，破碎的枝晶与“母体”分离，可在后续的冷却阶段作为形核质点。与此同时，由于电磁搅拌作用，溶质场和温度场分布均匀，抑制了成分过冷的产生，从而起到了细化晶粒的效果。
Abstract. Microstructures of a cast Ti-48A1-2Cr-2Nb alloy without melt treatment and with melt cycle treatment for 10, 15 and 20 cycles in solid-liquid region （1 480-1 510 ℃） were investigated by OM coptical microscope and SEM （scanning electron microscope）. The results show that the melt treatment has a significant role in the refinement of grain sizes in the alloys. The microstructure of the alloy is characterized by coarse columnar morphology without melt treatment, while it is characterized by small fine equiaxed grain from coarse lamellar cluster with the melt cycle treatment for 10, 15 and 20 cycles, and it is more uniformly distributed in the microstructure. At the faster heating stages in the melt cycle treatment process, the remelting of grain occurs, resulting in the separation of broken dendrite with the matrix to act as nuclei in subsequently solidification. Meanwhile, under the action of electromagnetic force, the solute field and temperature field are uniformly distributed to inhibit the occurrence of composition undercooling, which is responsible for the refinement of grain size.
出处
《特种铸造及有色合金》
CAS
CSCD
北大核心
2014年第3期243-246,共4页
Special Casting & Nonferrous Alloys
