两相介质剪切变形的实验研究

对(Mgx,Ni1-x)2GeO4橄榄石尖晶石两相混合物进行了剪切变形实验．实验在Paterson内伺服控制气体介质试验机中进行,围压为400MPa,温度为T＝1473K,应变率在10^—4到10^—5之间．剪切实验所用试件分为两种,一种试件为单层同结构比,其化学成分为(Mg0．9,Ni0,1)2GeO2,橄揽石和尖晶石的比例为77：23．另一种是两层不同结构比试件,其化学组成分别为(Mg0．9,Ni0,1)2GeO2和(Mg0．8,Ni0,1)2GeO2,试件中橄揽石和尖品石的比例分别为75：25和26：74．在单层同结构比试件的剪切变形实验中观测到,仅70％的总剪切变形就产生了很强的剪切带;而在两层介质的剪切试验中则观测到：一个小的化学成分的改变(10％),引起了大的相成分的改变(10％),同时产生了更大的剪切应变的差别(145％)．

RHEOLOGY OF OLIVINE-SPINEL MIXTURE IN THE SYSTEM (Mgx, Ni1-x)2 GeO4

The rheological behavior of the olivine-spinel two-phase mixtures of the system (Mgx,Ni1-x)2 GeO4 has been studied. The experiments were made at P = 400 MPa confining pressure and T =1473 K at constant load in a gas-medium apparatus with the strain rate ranging from 10-5 to 10-4. Two types of samples are used in the experiments. One is (Mg0.9, Ni0.2)2GeO4 with the olivine-spinel ratio 77:23. Another is a two layer sample with the chemical composition of (Mg0.9, Ni0.2)2GeO4 and (Mg0.9, Ni0.2)2GeO4 in each layer, respectively. While the olivine-spinel ratio is 75:25 and 26:74 in each layer, respectively. The test results show that with only 70% shear deformation, the intensive shear band was observed in the single layer shear deformation experiment and that with a small chemical composition difference (10%), the large phase difference (78%) as well as the huge strain difference (145%) was obtained in the two layer shear deformation experiment.