An investigation on supercooling directional solidification process of Cu-Ni single phase alloy

Supercooling directional solidification (SDS) is put fotward by combination of melt supercooling and conventional solidification by application of supercooling inheritance. On the self-designed SDS equipment, SDS of Cu-Ni alloy was achieved successfully The results are as follows f (i) The primary arm spacing is about 30 μm, the growth of secondary arms are strongly suppressed. The primary arm spacing is nearly the same as LMC method (GL=25 K/mm, V=500 pm/s), the primary stems are straight, fine and completed. with an inclination angle of about 5.8° (ii) A semi-quantitative T-T model is brought fotward to describe the dendrite growth rate V vs. undercooling AT The prediction of T-T model agrees well with experimental results. The formation of fine equiaxed dendrites, transition region and dendrite region can be explained successfully by △T-V-x relation of T-T model.     

灰翅麦茎蜂越冬幼虫抗寒性研究

测定了灰翅麦茎蜂越冬幼虫的过冷却点、结冰点和不同低温强度及持续时间的冷冻处理 ,得出如下结果 :灰翅麦茎蜂越冬幼虫过冷却点为 - 2 4 8± 1 2 5℃ ,结冰点为 14 9± 1 5 9℃ ;一定的低温条件下 ,处理时间愈长 ,化蛹率愈低 ;随着低温强度加大 ,化蛹率明显降低。并且探讨了青海省独特的气候特点对越冬幼虫的影响以及准确预测其发生量对指导大田防治成虫的重要性。