镍锗尖晶石扩散域高温蠕变性能的实验研究

DIFFUSIONAL HIGH-TEMPERATURE CREEP INNi_2GeO_4 SPINEL

利用人工合成的多晶材料研究了镍锗尖晶石在扩散域的高温蠕变性质.材料颗粒尺寸为0.5 μm到8 μm,压缩试件为圆柱状,使用气体介质围压试验机.常压蠕变试验过程中,围压为300MPa,温度为1123K到1523K,差应力在55～330MPa范围内.从实验结果得到的镍锗尖晶石在扩散域的流动律表明流动机制为颗粒边界的扩散蠕变(Coble蠕变).将橄榄石和尖晶石的蠕变数据外推到地球内部条件,粗粒时尖晶石强度远大于橄榄石,粒度减小时,尖晶石比橄榄石还要弱.

Diffusional high-temperature creep behavior in Ni2GeO4 spinel was investigated usingsynthetic polycrystalline aggregates with average grain sizes ranging from sub-micron to 8 microns.Cylindrical samples were deformed at constant load in a gas-medium apparatus at temperaturesranging from 1123 K to 1523 K and stresses ranging from 55 to 330MPa. Defussional creep flowlaw for Ni2GeO4 spinel suggests deformation by grain-boundary diffusion (Coble) creep. Whencreep data for olivine and spinel are normalized and extrapolated to Earth-like conditions, spinel(ringwoodite) is considerably stronger than olivine in the diffesion creep regime at coarse grainsize. However, when grain size is reduced, spinel can actually be weaker than olivine.