成分过冷

实验中获得的平界面耦合生长凝固速率要比成分过冷理论给出的临界凝固速度12.5μm／s要高。

The growth rate in experiment was higher than the critical velocity calculated by the CS ( Constitutional Supercooling ) theory .

其次概述了激光表面熔化区显微组织生成的有关理论&凝固热力学、非平衡状态层次、成分过冷判据和绝对稳定性判据和溶质扩散控制的凝固等。

Subsequently , theories related to the formation of microstructure in laser melted zones-thermodynamics in solidification , hierarchy of non-equilibrium , the constitutional supercooling criterion and the absolute stability criterion , solidification controlled by sol - ute diffusion are outlined .

由于成分过冷的形成，初晶TiC以树枝晶的形态生长。

Primary TiC grows in dendritic shape due to the formation of composition undercooling .

采用放置金属丝的方法，研究了型壁形核及成分过冷对A356形核的影响。

Effects of wall mechanisms and constitutional undercooling on nucleation were studied by inserting a stainless steel gauze in the mould .

提出了稀土元素细化镁及Mg-Al合金铸造组织的主要机理是：由于稀土元素的加入，使凝固过程中固／液界面前沿成分过冷度增大。

The mechanism of grain refine of rare earth on Mg-Al alloy is the increasing of undercooling degree between the solid / liquid interface during solidification and resulting in more nucleus .

讨论了定向凝固法制备YBCO超导体涉及的包晶转变与包晶反应、成分过冷、扩散控制生长模型、界面效应及定向凝固YBCO生长晶体学等问题。

Some basic material problems in preparing YBCO superconductor by directional solidification , including the peritectic transformation and peritectic reaction , the constitutional undercooling , a diffusion controlled growth model of YBCO , the interface effect and crystallography for directional solidification , were discussed in the present paper .

冷却过程中的成分过冷。

Compo-sition overcooling during cooling process .

给出了具有包晶反应的合金在定向凝固条件下的成分过冷判据式。

The constitutional supercooling criterion of alloys with peritectic reaction in the directional solidification was proposed .

Ⅲ结果表明，根据此模型计算出的温度梯度与利用成分过冷得出的结果是很相符的；

III The results demonstrate that the calculated temperature gradient is similar with the value evaluated by constituent supercooling theory .

而后通过考虑优势生长相界面前沿成分过冷区的形核，引入两相在凝固过程中的相互作用，对最高界面生长温度判据给出的组织及相选择图加以修正。

Afterwards the nucleation in the constitutional undercooled zone before the interface of leading phase is considered in order to make amendments to the constructed map .

在半固态模锻过程中，压力提高凝固速度，降低熔体的温度梯度，促进成分过冷。

In the process of semi-solid die forging , the pressure increases the speed of solidification , reduce the melt temperature gradient and promote composition undercooling .

由于重力偏析造成的异常成分过冷导致底缩现象，因此针对成因提出消除或减轻底缩的途径。

The reason causing bottom shrinkage is that gravitational segregation results in unusual composition undercooling , the method to eliminate or ease bottom shrinkage is given .

结果表明：在大的凝固速度条件下，凝固界面前沿存在成分过冷区，液-液相分解在此区域内进行；

It is shown that at a high solidification velocity a constitutional supercooling region appears in front of the solid / liquid interface where the liquid liquid decomposition takes place .

当过热处理温度T+高于合金的临界过热温度T+C时，随着T+提高，成分过冷度有显著增大，又导致了平界面的失稳。

When superheating temperature T + is higher than the temperature T + c , with T + increasing the concentration gradient in liquid increases significantly , which decreases the planer interface stability .

晶粒采用连续形核公式异质形核，通过捕获四周的液态元胞晶粒生长，考虑了温度梯度和成分过冷对晶粒形核和生长的影响。

Crystals are heterogeneous nucleated by continuous forming formula , and grown up by capturing the liquid state cells all around , and the effect of temperature gradient and ingredient overcooling was considered .

采用胞元自动机方法，在综合考虑了成分过冷、曲率过冷和界面能各向异性后，通过在界面上施加不同振幅和波长的扰动，对枝晶的分枝机制进行了模拟计算。

Under the consideration of concentration undercooling , curvature undercooling and the anisotrophy of interfacial energy , Cellular Automaton method was applied to simulate the dendrite branching mechanism by imposing perturbation with different amplitude and wavelength .

微观区域内的初始温度分布由周围的宏观单元温度插值得到，界面过冷包含热过冷、成分过冷和曲率过冷。

The initial distribution of the temperature in the micro domain is obtained by interpolating the temperature of the cells near the selected cell and the interface undercooling is considered to be the sum of thermal , solute and curvature effects .

Fe74Al4Sn2P10Si4B4C2合金能达到较大的过冷度，具有较高的约化玻璃转变温度（接近共晶合金成分）和过冷合金熔体的二步相析出有利于块体非晶合金和块体纳米晶合金的形成。

Larger undercooling , higher reduced glass transition temperature ( near-eutectic composition ) and two-step phase precipitation of undercooling alloy melt favor the formation of bulk amorphous and bulk nanocrystalline alloys .

研究表明细等轴晶的形成要求特殊的化学成分（含Zr，Li元素）和一定的凝固条件（小的成分过冷度）。

It was found that the existence of a particular solidification condition ( i.e. smaller constitutional undercooling degree ) as well as the elements of zirconium and lithium was necessary for the fine equiaxed smooth grains to form .