A New Explanation for the Effect of Dynamic Strain Aging on Negative Strain Rate Sensitivity in Fe–30Mn–9Al–1C Steel

In this study, the evolution of the mechanical properties of Fe–30Mn–9Al–1C steel has been determined in tensile tests at strain rates of 10−4 to 102 s−1. The results show that the strain rate sensitivity becomes a negative value when the strain rate exceeds 100 s−1 and this abnormal evolution is attributed to the occurrence of dynamic strain aging. Due to the presence of intergranular κ-carbides, the fracture modes of steel include ductile fracture and intergranular fracture. The values of dislocation arrangement parameter M were obtained using a modified Williamson–Hall plot. It has been found that once the strain rate sensitivity becomes negative, the interaction of dislocations in the steel is weakened and the free movement of dislocation is enhanced. Adiabatic heating promotes the dynamic recovery of steel at a high strain rate.

Study on Figuring Technique on a Back-Strap Loom of Li Nationality

Figuring technique on a back-strap loom of Li nationality is a key to study on the most primitive form of figuring in ancient China. However, the previous studies on figuring technique on a back-strap loom of Li nationality were not very clear, and led to much misunderstanding. Based on our investigation on the spot of Hainan province, we introduce the arrangement principle of weave structure of brocade of Li nationality and the operation principle of figuring technique on the back-strap loom, at last we explain the operational process of figuring technique on a back-strap loom of Li nationality. It is concluded that figuring technique on a back-strap loom of Li nationality employs the dislocation arrangement of figuring parts.

Dislocations in thin metal films observed with X-ray diffraction

ABSTRACTX-ray diffraction has been used to measure the stress, the crystallite size and the dislocation distribution in thin metal layers. By measuring two orders of a reflection, the contribution of the size distribution to the diffraction line broadening can be eliminated. A model equation is fitted to the strain Fourier coefficients of the diffraction line from which the dislocation arrangement can be obtained. For untextured nickel on steel or on silicon the dislocation densities have been obtained. It is demonstrated that for highly textured layers more information can be obtained than for untextured layers. It was found that a heated molybdenum layer on oxidized silicon showed only inclined screw dislocations.