Differential stress‐induced melt migration: An experimental approach
Differential stress‐induced melt migration: An experimental approach
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差异应力引起的熔体迁移：一种实验方法
DOI：
10.1029/jb095ib05p06979
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发表时间：
1990
影响因子：
--
通讯作者：
R. Cooper
中科院分区：
文献类型：
--
作者：
R. Cooper
应力差状态的非平衡分量的梯度将导致熔体相在织构（准）平衡的部分熔体中的迁移。提出了一种实验方法来成像这种变形引起的熔体迁移。两相固液聚合物梁（通过玻璃-陶瓷技术制备的）具有MgSiO 3的主晶相（正顽火辉石与有限量的斜顽火辉石共生体）与钠铝硅酸盐玻璃处于化学和结构平衡，经受四点弯曲;一阶热力学分析，基于晶界之间的能量平衡（固-固界面）和固-液界面的概念表明熔体相从处于压缩主应力下的试样的那一侧流动到处于拉伸主应力下的试样侧。当固-液聚集体的特征在于牛顿流变学（即，通过溶解-沉淀-增强的扩散蠕变机制发生变形），熔体迁移作为伴随试样弯曲流动的大变形瞬态容易观察到。因此，熔体迁移的特征在于两相系统中的完全可恢复的滞弹性应变;部分熔融的梁的流变学由eT（t）=e0[1-exp（-Bt）]+ estecss良好地建模，其中eT是总非弹性应变，e0是由于熔体迁移引起的总滞弹性应变，estecss是两相聚集体的稳态应变速率，t是时间，B是液相粘度或两相聚集体流变学（粘度）的函数。在这里报道的实验中，熔体迁移被证明是由结晶残留物的压缩和/或膨胀的动力学速率限制的。的实验方法的影响，基于双折射模型的熔体输送和偏析进行了讨论。
A gradient in the dilatational component of a differential state of stress will cause migration of the melt phase in a texturally (quasi)equilibrated partial melt. An experimental approach to image such deformation-induced melt migration is presented. Two-phase, solid-liquid aggregate beams (prepared by a glass-ceramic technique) having a primary crystalline phase of MgSiO3 (orthoenstatite with a limited amount of clinoenstatite intergrowths) in chemical and textural equilibrium with a sodium aluminosilicate glass are subjected to four-point flexure; a first-order thermodynamic analysis, based on the energy balance between grain boundaries (solid-solid interfaces) and solid-liquid interfaces, indicates that the melt phase flows from that side of the specimen under a compressive principal stress to the specimen side under a tensile principal stress. When the solid-liquid aggregate is characterized by a Newtonian rheology (i.e., the deformation occurs via a solution-precipitation-enhanced diffusional creep mechanism), the melt migration is easily observed as a large deformation transient accompanying the flexural flow of a specimen. The melt migration is thus characterized as a completely recoverable, anelastic strain in the two-phase system; the rheology of the partially molten beams is well modelled by eT(t)=e0[1−exp(−Bt)]+e˙sst where eT is the total inelastic strain, e0 is the total anelastic strain due to melt migration, e˙ss is the steady-state strain rate for the two-phase aggregate, t is time and B is a function of either the viscosity of the liquid phase or of the rheology (viscosity) of the two-phase aggregate. In the experiments reported here, the melt migration is shown to be rate limited by the kinetics of compaction and/or dilation of the crystalline residuum. The impact of the experimental approach on compaction-based models of melt transport and segregation is discussed.