| Nowadays, development of new environmentally-friendly energy alternative materials has been urgent due to the increasingly serious energy crisis. Thermoelectric materials are semiconducting functional materials with wide application prospect, which can interconvert heat and electricity directly. Among them, skutterudites compounds is one of the narrow bandgap semiconductor materials with open structure, it has high Seebeck coefficient and high electrical conductivity and can became be a promising thermoelectric material used in medium temperature by some special optimization method. Under service conditions, thermoelectric devices often suffer from the cyclic thermal loading and cyclic thermal stress loading. All of these loads not only cause damage to the devices, but also reduce its service life. Better understanding of the fatigue behavior of skutterudits compounds is essential for reliability estimation and service life prediction of thermoelectric devices.In this work, Ce0.5Fe1.5Co2.5Sb2compounds CoSb3are taken as the research object, they were prepared by using melting method combined with the spark plasma sintering technique. After cutting, grinding and polishing, the specimens were obtained. All tests are divided into three types. The first tests are static compression tests and three-poind-bending tests. The second type tests are stress-controlled low-cycle fatigue tests. The last tests are residual strength degradation tests. An MTS810servohydraulic machine and Instron5882machie were used for the test.First the static compression tests and three-point-bending tests were condcted. The purpose of these tests was to obtain the compressive strength, flexural strength and Young's modules. Compression-compression low cycle fatigue tests were then conducted. A sinusoidal waceform of constant amplitude with a frequency of2Hz and stress ratio R of0.1was employed. Tests were carried out at room temperature and in air. The maximum stress of the cyclic loading was chosed to be60%-90%of the static compressive strength. The surfaces and fracture surfaces of the specimens were observed by scanning electron microscopy. Based on surface crack observation and fatigue fracture surface analyses, fatigue cracks initiated from pre-existing defects in the specimen surface due to stress concentration. The fatigue fracture surface was basically characterized by intergranular fracture, which suggests brittle characteristics of the materials. Besides, thegrain size remains basically unchanged afterfatigue loading.All fatigue life tests date exhibit significant scatter, so in this study, the static strength, fatigue life are asuumed to be presented by two-parameter normal distribution. The S-N curve of CoSb3and Ceo.5Fe1.5Co2.5Sb2were described by two parameters linear equation. Based on statictical data processing, the coefficents of S-N equations were obtained under different probability. Thus P-S-N equation the materials are obtained. Further, fatigue tests were employed to analyze the influence the stress ration, the loading frequency and loading waveform (triangular wave, square wave and sine waveform) on the fatigue life of CoSb3. The static fatigue tests were also carried out. The results showed, under the same conditions, the fatigue lifes of static fatigue is bigger than those of cyclic fatigue.Lastly, residual strength degradation tests of CoSb3were employed. The tests results can describe the degradation behaviour and can analyze the effect of the cyclic loading on the residual strength. Based on the test results and probabilistic analysis method, the P-R-N curves of CoSb3were obtained. The curves can predict the residual strength at a given number of fatigues loading cycles with given probability. The residual fatigue life also can be predicted based on P-R-N curves and the linear accumulative damage rule.
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