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采用单辊急冷技术实现了NiAl-Mo三元两相共晶合金的快速凝固,同时与常规条件下的凝固组织进行了对比研究.实验发现,单辊急冷的合金条带与常规条件的凝固样品均由B2结构的NiAl金属间化合物和bcc结构的Mo固溶体两相组成,两相均具有(110)晶面优先生长的趋势,并呈现出(110)NiAl//(110)Mo取向关系.常规条件下得到的微观结构主要由规则的两相共晶组织组成,形成了类似菊花状的共晶胞.而单辊急冷条件下形成的组织结构主要是由近辊面的柱状晶区和近自由面的等轴晶区组成的凝固组织.理论计算发现,合金熔体的单辊辊速由10m/s增大至50m/s后,其冷却速率从1.01×107K/s逐渐增大到2.46×107K/s,冷却速率明显高于常规铸造过程,因而形成了差别很大的凝固组织.随着辊速(冷却速率)的增加,合金条带的厚度从54.4μm减小至22μm,近辊面柱状晶区的厚度所占比例也逐渐增大,晶粒发生了明显细化.
The rapid solidification of NiAl-Mo ternary two-phase eutectic alloy was achieved by single-roll quenching technique, and compared with the solidified structure under conventional conditions.It was found that single-roll quenched alloy strip and conventional conditions of solidification samples Both of the NiAl intermetallic compounds of B2 structure and the Mo solid solution of bcc structure are two phases, and both have the preferential growth of (110) crystal plane and show a (110) NiAl // (110) Mo orientation relationship. Under the conditions of the microstructure is mainly composed of regular two-phase eutectic structure, forming a similar chrysanthemum-like eutectic cell.And single-roll quenching conditions formed mainly by the organization near the columnar columnar grain and nearly free Surface equiaxed zone.The theoretical calculation shows that the cooling rate increases from 1.01 × 107K / s to 2.46 × l after the single roller speed of alloy melt increases from 10m / s to 50m / s, 107K / s, the cooling rate was significantly higher than the conventional casting process, resulting in a very different solidified structure.With the increase of the roll speed (cooling rate), the thickness of the alloy strip decreased from 54.4μm to 22μm, the near roll surface The thickness of the columnar region also gradually increased the proportion of the grain occurred Obvious refinement.