第六章 纯晶体的凝固

Chapter 6 Phase diagram of single-component and Solidification

for pure metal

作业1：The solid-liquid interfacial energy of pure silver is 0.126J/m 2. The latent heat of melting is 104.6J/g. The melting point of pure silver is 961℃. The density of solid/liquid silver at the melting point is 10.5g/cm 3

. (15points)

(1) What is the value of the critical radius at 700℃? (2) What is the value of ΔG * at this radius?

作业2：This diagram is for a hypothetical embryo of silver growing against an arbitrary

mold wall. With the aid of this diagram,

(a)

Compute the angle of contact, θ, of the embryo with the mold wall. (b) Determine the magnitude of the factor that may be used to convert the

homogeneous free energy needed to obtain a nucleus into that of the corresponding heterogeneous free energy.

作业3: 已知纯铜的熔化潜热为1.88×109J/M 2,熔点为1089℃，点阵常数为3.4167Å, 发生

均匀形核过冷度为230K ，21SL /10*44.1m J -＝σ

。求铜的临界晶核半径⨯γ及临界晶核中所含的铜原子数。

作业4：已知锌的熔点为419℃，其结晶潜热为7×108J/m 3,液固界面能2/06.0m J ＝σ，

锌的原子量为65.4，密度为7.18g/cm 3,试计算锌在350℃结晶后的临界晶核半径，并说明晶核内有多少个锌原子？

作业5：金的熔点为1064℃，溶化潜热为12.8KJ/mol, 若液态金在1000℃时发生结晶，其

临界晶核半径m 10*10*3.43-=γ

，试计算金属的液固界面能。

作业6：解释金属结晶时，为什么会产生过冷？

作业7：在均匀形核时，若设晶核形状为边长a 的立方体，试求其临界晶核半径及形核功。