NOVEL APPARATUS USING SCANNING LASER EXTENSOMETRY FOR HIGH-TEMPERATURE MATERIALS TESTING AND ITS APPLICATION TO MECHANICAL SPECTROSCOPY STUDIES ON METAL MATRIX COMPOSITES

在这个为期两年的研究项目中，根据08555161号合同，我们得到了文部科学省科学研究补助金（A）（2）的支持，在标准伺服液压机上构建了一个用于高温材料测试的新型实验装置;它的特点是一个基于便携式“扫描激光卡尺”的高精度引伸测量系统并使我们能够测量材料的动态滞弹性响应的温度范围从300至1373 K下的低频（1cHz-1dHz）亚共振条件下的循环单轴加载。用该装置对Al-SiC、Al-9Al_2O_32B_2O_3和Ni-ZrO_2系金属陶瓷复合材料的动态杨氏模量和内耗进行了测量，这些材料的实验数据都显示出明显的滞弹性弛豫现象，并在两个完全分离的温度范围内得到了明显的滞弹性弛豫。 ...更多信息 温度范围内，即两个内摩擦峰一起观察到的动态杨氏模量显着下降。这些松弛现象的动力学方面进行了详细分析，这涉及到的活化能和指前因子的确定从频率依赖性的峰顶温度的内部摩擦的松弛时间，和比较的实验确定的动力学参数与理论模型的预测。分析确定了所观察到的峰值之一，作为众所周知的柯峰由于粘性晶界滑动。作为一个可能的起源的剩余的峰值，我们提出了应力导向的扩散质量流沿着金属陶瓷相边界，并进行了基于微观力学的计算，从而得出理论表达式的动态杨氏模量和复合材料的内耗。理论与实验的比较也证明了这种弛豫机制的现实性。少

In this two-year research project, supported by a Grant-in-Aid for Scientific Research (A) (2) from the Ministry of Education, Science, Sports and Culture under Contract 08555161, we have constructed a novel experimental setup for high-temperature materials testing on a standard servo-hydraulic machine ; it features a high-precision extensometric system based on a portable "scanning laser caliper" and enabls us to measure the dynamic anelastic response of a material over a temperature range from 300 to 1373 K under low-frequency (1cHz-1dHz) subrresonant conditions of cyclic uniaxial loading. Using the apparatus, the measurements of dynamic Young's modulus and internal friction have been carried out on metal-ceramic composite materials including Al-SiC,Al-9Al_2O_32B_2O_3 and Ni-ZrO_2 systems ; the experimental data on these materials all show clear evidence of anelastic relaxation in two well-separated temperature all show clear evidence of anelastic relaxation in two well-separated tem … More perature ranges, i.e.two internal friction peaks are observed together with marked decreases in dynamic Young's modulus. Kinetic aspects of these relaxation phenomena have been analyzed in detail ; this involves the determination of the activation energy and pre-exponential factor of the relaxation time from the frequency dependence of the peak-top temperature of internal friction, and the comparison of the experimentally determined kinetic parameters with predictions of theoretical models. The analysis identifies one of the observed peaks as the well-known Ke's peak due to viscous grain-boundary sliding. As a possible origin of the remaining peak, we raise the stress-directed diffusive mass flow along metal-ceramic phase boundaries, and make a micromechanics-based calculation to derive theoretical expressions for the resulting dynamic Young's modulus and internal friction of composite materials. The comparison between theory and experiment also proves the actuality of this relaxation mechanism. Less