| Title |
A Numerical Investigation of Elastic and Plastic Properties in Nanocrystalline Materials |
| Authors |
김형섭(Hyoung Seop Kim); 홍순직(Soon Jik Hong) |
| Abstract |
In order to investigate the effect of grain size on the overall elastic and plastic properties of nanocrystalline materials in which the grain size ranges typically from a few nanometers to a few tens of nanometers, the elasto-plastic finite element method was used. The tensile deformation behaviors of the unit cell composite materials composed of crystalline of various sizes and grain boundary region of 1 nm width have been analyzed. The grain boundary region had a lower elastic modulus and a higher yield strength than the crystalline and the materials were assumed to be elastic-perfect-plastic because of the small grain size. According to the calculated results, a drop in the grain size from 100 nm to 2 nm increased the yield stress and decreased the elastic modulus. The yield stress-(grain size) -1/2 shape is S curve which fitted well with the mixture rule based on the volume fraction. Therefore, the exponent of Hall-Petch equation can be - 1 or -1/2, and the gradient of the curve can undergo a change according to the range of the grain size. |