B L Zhou/ Materials Science and Engineering C 11 (2000)13-18 4+4 Distance from outer surface (mm) matrix wound Fig. 7. Fibre volume fraction of bamboo(a) before and (O)after compression(compressive ratio is 0.49)[22] Coordinate Fig. 5. A schematic diagram of the growth process in the first-order phase transition theory [21] Electropulsing also improved the ductility of metal foils, which caused a significant increase of elongation of aluminum thin foils under stress in both cold-worked and self-organization processes of open system. One's life can annealed states only last for a week without eating and drinking, but several decades age can be obtained by regular living with 3.5. A possible way to recover the fatigue of materials input of energy and substance(food) in due time. It gives /17, 18, 20/ us a new way to simulate in the case of materials treat Electropulsing of high current density can be taken as a kind of transient input of energy, to cause reorganization 3. 4. Influence of high-intensity electropulsing on the work- of the microstructure of the material and to improve ing life of materials /19/ fatigue property [20]. Mild steel of 0. 13%C is taken testing material. The fatigue life of specimens are com- From the view point of structure evolution, the fatigue pared in Table 1. It can be seen from Table I that th process of material is the nucleation and growing process fatigue life of the fourth group is significantly raised of a new structure in an originally homogeneous structure The mechanism of this phenomenon is thought to be under the driving force of external load. The fatigue life of related to the decrease of number and width of persistent material corresponds to the growing time of the new phase slip band(PsB) by electropulsing [ 19] rom 0 to the critical value It means that the nucleation and growing of new phase 3.6. Healing effect of electropulsing in metals /217 ill make the free energy of system increase, that is, the existence of electropulsing prevents the nucleation and Now we consider a metallic material with an injur growing of new phase somewhere. The electric current takes the injured part far ActeD b《 e c&.dtmm (b) Fig. 6. Optical photographs of cross-sections of (a)normal bamboo and(b)reformed bamboo [22]16 B.L. ZhourMaterials Science and Engineering C 11 2000 13–18 ( ) Fig. 5. A schematic diagram of the growth process in the first-order phase transition theory 21 . w x self-organization processes of open system. One’s life can only last for a week without eating and drinking, but several decades age can be obtained by regular living with input of energy and substance food in due time. It gives Ž . us a new way to simulate in the case of materials treat￾ment. 3.4. Influence of high-intensity electropulsing on the work￾ing life of materials 19 [ ] From the view point of structure evolution, the fatigue process of material is the nucleation and growing process of a new structure in an originally homogeneous structure under the driving force of external load. The fatigue life of material corresponds to the growing time of the new phase from 0 to the critical value. It means that the nucleation and growing of new phase will make the free energy of system increase, that is, the existence of electropulsing prevents the nucleation and growing of new phase. Fig. 7. Fibre volume fraction of bamboo Ž. Ž. ^ before and v after compression compressive ratio is 0.49 22 . Ž . w x Electropulsing also improved the ductility of metal foils, which caused a significant increase of elongation of aluminum thin foils under stress in both cold-worked and annealed states. 3.5. A possible way to recoÕer the fatigue of materials [ ] 17,18,20 Electropulsing of high current density can be taken as a kind of transient input of energy, to cause reorganization of the microstructure of the material and to improve its fatigue property 20 . Mild steel of 0.13% C is taken as w x testing material. The fatigue life of specimens are com￾pared in Table 1. It can be seen from Table 1 that the fatigue life of the fourth group is significantly raised. The mechanism of this phenomenon is thought to be related to the decrease of number and width of persistent slip band PSB by electropulsing 19 . Ž . w x 3.6. Healing effect of electropulsing in metals 21 [ ] Now we consider a metallic material with an injury somewhere. The electric current takes the injured part far Fig. 6. Optical photographs of cross-sections of a normal bamboo and b reformed bamboo 22 . Ž. Ž. w x