Materials World Network: Interaction of time- and load history dependent degradation of multilayered materials subjected to high temperatures

多层材料在高温下表现出与时间和温度相关的演化，如相的互扩散、沉淀和溶解，以及化学反应，特别是在不同材料的界面上。在大多数应用中，循环载荷是叠加的。时变过程与循环荷载引起的退化之间的相互作用是高度非线性的。因此，在实际载荷条件下，很难使用常用的加速试验方法进行寿命评估。另一方面，由于试验时间较长，在实验室环境中再现真实载荷谱和真实时间尺度在大多数情况下是不可能或不现实的。我们建议开发一种实验和数值相结合的技术，用于高温下具有不同材料接头的材料系统的加速试验和寿命预测。这种方法结合了基础材料科学和应用力学。将进行一套精心挑选的热载荷和循环载荷组合的测试序列，随后将通过微观和微观分析方法研究各自的降解状态。将确定潜在的机制，并将其用于材料行为的基于机制的建模和数值模拟。通过连续的实验和模拟，有望获得描述调节机构相互作用的参数，这些参数将用于寿命评估。数值模拟将减少实验工作量和所需的测试时间。

Multilayered materials subjected to high temperatures exhibit time and temperature dependent evolution such as interdiffusion, precipitating and dissolution of phases, along with chemical reactions especially at the interfaces of dissimilar materials. In most applications cycling loads are superposed. The interaction between time-dependent processes and degradation due to cyclic loads is highly non-linear. Thus, it is difficult to use here common approaches of accelerated testing for lifetime assessment under realistic loading conditions. On the other hand, reproducing realistic load spectra and realistic time scales in laboratory environment is in most cases not possible or impractical because of long testing times.We propose to develop a combined experimental and numerical technique for accelerated testing and life-time prediction of material systems with joints of dissimilar materials at high temperatures. This method incorporates fundamental materials science and applied mechanics. A set of carefully selected test sequences with combined thermal and cyclic loading will be conducted and subsequently, the respective degradation status will be investigated by means of microscopic and microanalytic methods. The underlying mechanisms will be identified and used for mechanism based modelling and numerical simulation of the materials behaviour. From successive experiments and simulations it is expected to achieve parameters describing the interaction of the governing mechanisms, which will be used for lifetime assessment. The numerical simulations will reduce the experimental effort and the required testing time.