The autonomous repair mechanism of creep cavitation during high-temperature deformation has been investigated in Fe-Au and Fe-Au-B-N alloys. Combined electron-microscopy techniques and atom probe tomography reveal how the improved creep properties result from Au precipitation within the creep cavities, preferentially formed on grain boundaries oriented perpendicular to the applied stress. The s...

The present paper will describe an approach for the simultaneous real-time compensation of hysteresis, creep and force-dependence effects of a piezoelectric stack actuator by a feed-forward controller. The basis of the feed-forward controller is given by so-called complex creep and hysteresis operators, which when adequately implemented, lead to a precise model of the creep and hysteresis chara...

The Steady state creep behaviour of a functionally graded cylinder made of isotropic composite containing varying distribution of silicon carbide particles has been investigated by a mathematical model. The creep behaviour of the FGM is described by a Norton's Power law. The effect of varying distribution of SiCP particles of creep stresses and creep rates in the FGM cylinder has been anal...

We present experimental evidence that pressure solution creep does not establish a steady-state interface microstructure as previously thought. Conversely, pressure solution controlled strain and the characteristic length scale of interface microstructures grow as the cubic root of time. Transient creep with the same scaling is known in metallurgy (Andrade creep). The apparent universal scaling...

.............................................................................................................................. iii ACKNOWLEDGMENTS ......................................................................................................... iv TABLE OF CONTENTS ............................................................................................................ v LIST OF FIGU...

The creep-fatigue interaction has been studied and innovative mathematical models are proposed to predict the operating life of aircraft components, specifically gas turbine blades subject to creep-fatigue at high temperatures. The historical evolution of the creep-fatigue lifetime prediction is given in order to place the present study in the context. A literature review of the life estimation...

Static and completely reversed cyclic creep acceleration characteristics of Al – 22 wt% Ag alloy were investigated using a modified tensile testing machine. Different amplitudes of reversed cyclic stress (σrev) ranging from 7.2 to 10.2 MPa at different working temperatures ranging from 353 K to 413 K were performed. To get a relation between aging temperature and threshold stress (σth) for cycl...

Reactive infiltration processing was used to fabricate bulk NiAl and fiber-reinforced NiAl composites. Homogenous, pore-free materials were obtained by chemical reaction between nickel and aluminum after complete infiltration with liquid aluminum of preforms of nickel wires (containing tungsten wires for the composites) with low surface-to-volume ratio, high permeability, and regular infiltrati...

steady state creep of the alloy was in a thermodynamical steady state, (2) which configuration of the dislocation network was contributing to the creep strength, and (3) which change in the dislocation network was the cause of the creep recovery. Specimens were furnace-cooled under stress and then observed by transmission electron microscopy. The creep stress was reduced during the test and the...

AIM The aim of this study was to identify adaptations in muscle activity distribution to spinal tissue creep in presence of muscle fatigue. METHODS Twenty-three healthy participants performed a fatigue task before and after 30 minutes of passive spinal tissue deformation in flexion. Right and left erector spinae activity was recorded using large-arrays surface electromyography (EMG). To chara...