Papers by Author: Ya Ping Zong

Abstract: Equal channel angular extrusion (ECAE) is an effective means of producing ultrafine-grained materials with extraordinary mechanical properties. Texture evolution and microstructure in pure copper single crystals processed by ECAE for up to five passes via route C are investigated to understand mechanisms of plastic deformation and grain refinement during ECAE. The experimental textures after the third pass ECAE process recovers that after one pass ECAE process. The main textures approaches a stable one after four passes of ECAE process via Route C while the intensity of main texture components decreases gradually. Local TEM-OIM measurements shows that grain subdivision in ECAE-processed samples occurs with the formation of many low angle grain boundaries.

Abstract: A specimen current heating sintering process was employed to manufacture SiC particulate reinforced iron matrix composite. The results show that mechanical properties of the composite can be improved significantly with increasing pressure level, voltage, sintering time. It is found that short sintering time, fast heating and uniformly heating, surface activation of particles can be accomplished in specimen current heating hot press sintering to avoid oxidation degradation of Fe powder, and to produce fine microstructure, which contribute the main reasons for achieving higher density and higher properties. The best properties achieved so far for the composite are: density is 99.90%, Brinell hardness is 416HB and tensile strength is 838MPa.

Abstract: The orientation evolution in Copper single crystal during ECAE (in Route C) has been investigated experimentally for 90° die angle by X-ray diffraction and TEM-OIM. It is shown that after the previous three passes of ECAE, orientation evolutes with similar mechanism to the simple shear deformation. The grain subdivision occurs with the appearance of many low angle grain boundaries. After four times extrusions the ED of the samples remains stable, their ND rotates around the ED by about 20°. After five times extrusions the main texture component remains stable.