Slip (materials science)

About: Slip (materials science) is a research topic. Over the lifetime, 46439 publications have been published within this topic receiving 1067099 citations. The topic is also known as: dislocation slip.

Triggered aseismic fault slip from nearby earthquakes, static or dynamic effect?

Abstract: [1] Observations show that an earthquake can affect aseismic slip behavior of nearby faults and produce ‘‘triggered aseismic fault slip.’’ Two types of stress changes are often examined by researchers as possible triggering sources. One is the static stress change associated with the faulting process and the other is the dynamic stress change or transient deformation generated by the passage of seismic waves. No consensus has been reached, however, regarding the mechanism(s) of triggered aseismic fault slip. We evaluate the possible triggering role of static stress changes by examining observations made after 10 large earthquakes in California. Most of the nearby fault segments that slipped aseismically were encouraged to move by the imposed positive changes in static Coulomb Failure Stress (CFS). Nonetheless, three discrepancies or failures with this model exist, which implies that static stress triggering either is or is not the sole mechanism causing the observed triggered slip. We then use a spring-slider system as a simplified fault model to study its slip behavior and the impact of transient (dynamic) loading on it. We show that a two-state-variable rate-dependent and state-dependent frictional law can generate creep events. Transient loads are then put into the system. Certain types of them can cause a large time advance of (or trigger) the next creep event. While our work examines triggered creep events near the surface, it may well have implications for the occurrence of similar events near the bottom of the seismogenic zone where a transition in frictional stability occurs. INDEX TERMS: 7209 Seismology: Earthquake dynamics and mechanics; 7260 Seismology: Theory and modeling; 8168 Tectonophysics: Evolution of the Earth: Stresses—general

Formation mechanism of the hierarchic structure in the lath martensite phase in steels

Abstract: Martensitic transformation is the phase transformation accompanying orderly shear deformation without atomic diffusion. The structures made by martensitic transformation are classified as thin plate, lens or lath in steels. The mechanism by which the hierarchic microstructure in the lath martensite phase forms has heretofore not been understood. We have made clear the mechanism by considering, independently, two plastic deformations using the slip deformation model proposed by Khachaturyan, and present herein a deformation matrix for each of the six crystallographic variants in a packet of the hierarchic structure. Our results are quantitatively consistent with experimental results for the Kurdjumov–Sachs (K-S) crystal orientation relationship and habit plane. Furthermore, the important points of our study are as follows: the origin of the sub-block structure and the specific combination of the sub-block structure are clarified; the laths existing in a block can be explained; and deviations between the di...

The size effect and plastic deformation mechanism transition in the nanolayered polycrystalline metallic multilayers

Abstract: The strength and deformation mechanisms of the nanolayered polycrystalline metallic multilayers (NPMMs) are investigated via molecular dynamics simulation, with special attentions to the coupling effect of grain size and layer thickness. The results indicate that the strength of multilayers does not always increases sensitively with the decrease of layer thickness or grain size, and the smaller one of them governs substantially the size effect on the strength. Due to the constraint of GBs and phase interface to gilding dislocations, there are several possible deformation mechanisms, which can govern the strength of NPMMs, including the confined partial dislocation slip, confined extended dislocation slip, and confined grain boundary slip. With the increase or decrease of the characteristic size of multilayers (i.e., layer thickness or grain size), the dominant deformation mechanism changes from one to another, resulting in very intricate size effect on the strength of multilayers. The underlying reason of...

Anisotropic plasticity and cavity growth during upset forging of Ti-6Al-4V

Abstract: Orientation imaging microscopy was used to determine the effect of local crystallographic texture on the nucleation and growth of cavities in Ti–6Al–4V with a colony-α microstructure during upset forging to a 35% height reduction at 815 °C and a strain rate of 0.1 s −1 . In contrast to uniaxial deformation, the stress–strain history in the bulged equatorial region was complex. Cavities developed preferentially along prior-β grain boundaries nominally perpendicular to principal stress directions, particularly where there were 90° colony misorientations, even in regions where global secondary-tension stresses were small or even negative. High cavity nucleation and growth rates were strongly correlated with the 90°-misoriented colonies, regardless of the orientations of the adjacent colonies. A rationale was developed to account for the particular sensitivity of 90°-misorientations based on colony orientation, slip systems, Taylor and Schmid factors, strain ratio and deformation history. Colonies with orientations in which prism slip was highly favored were stable and exhibited strong plastic anisotropy. When a neighboring colony had a 90°-misorientation, highly non-uniform strains developed in the boundary region, resulting in large triaxial stress concentrations that facilitated cavity nucleation and plastic strain conditions that favored cavity growth.