A new aluminium alloy laminate characterized by high damping, corrosion resistance and weldablity was developed. The laminate designed for required aforesaid functions was actually a composite material, which was made...A new aluminium alloy laminate characterized by high damping, corrosion resistance and weldablity was developed. The laminate designed for required aforesaid functions was actually a composite material, which was made of two anti corrosive layers (Al), two damping layers (ZnAl alloy) and one reinforcing layer (AlMg alloy) by hot rolling. The damping characteristics were studied and it was found that there was an internal friction peak at about 50 ℃ on internal fraction vs temperature curve for the laminate. For this reason, the activation energy of the peak was calculated. The origin and damping mechanism for this peak was researched by means of SEM, TEM, X ray and DSC. It is considered that the peak is caused by the interaction between dislocations and point defects in damping layers (AlZn alloy). i.e. by the movement of dislocations dragging point defects under the action of thermal activation. The laminate is remained at room temperature for a long time, it will weaken or even disappear with the restoration of the crystal microstructure and the reduction of the dislocation density in the ZnAl alloy layers. The mechanism of the peak is in conformity with that of the dislocation induced damping. [展开更多
The new forming process of AA6061 alloy tube, including solution treatment, granule medium internal high-pressure forming and aging treatment, was developed. The AA6061 alloy tube via heat treatment satisfied the form...The new forming process of AA6061 alloy tube, including solution treatment, granule medium internal high-pressure forming and aging treatment, was developed. The AA6061 alloy tube via heat treatment satisfied the forming requirement, and the granule medium internal high pressure forming method for AA6061 alloy tube was also realized by using convenient implementation with low requirement of equipment and flexible design of product. At a solution temperature of 560℃ and time of 120 min, the elongation of the AA6061 extruded tube increases by 300% and the strength and the hardness dramatically decrease too. Therefore, the AA6061 alloy tube meets the requirement of internal high-pressure forming because of the improvement of formability. The experiments shows that the strength and hardness of AA6061 alloy workpiece recover to that of the as-received alloy at an aging temperature of 180℃ and time of 360 min, and the strength of AA6061 alloy workpiece is equal to the base alloy. The typical parts of convex ring tube, stepped shaft tube and hexagonal tube were successfully produced in lab by using the present forming method. The forming tests show that the maximum expansion ratio(MER) of the AA6061 extruded tube increases by 25.5% and the material properties of formed AA6061 alloy tube reached the performance of as-received alloy.展开更多
Effect of solution treatment temperature on transformations and two way memory, effect in a Ti- 55.2 wt-%Ni alloy was investigated. The results show that with increasing the solution treatment temperature (T_s), two w...Effect of solution treatment temperature on transformations and two way memory, effect in a Ti- 55.2 wt-%Ni alloy was investigated. The results show that with increasing the solution treatment temperature (T_s), two way memory effect (TWME) decreases continuously and temperatures of martensite and reverse, martensite transformations (MR) rise, but the temperature of R start trans- formation (parent→R) does not change. The results of the internal friction measurements indicate that when T_s=1073 K, internal friction peaks of MR and P→R transformations are larger than those of the specimens after solution-treatments at 973 and 1173 K. With increasing T_s, the de- crease of TWME can be attributed to that the defect stress field caused by the rolling fades out grad- ually and preferential martensite variants, which fit into the defect stress field, decrease. The changes of transformation temperatures and internal friction peaks with T_s are closely related to the change of defect numbers.展开更多
The damping capacity of the shape memory alloy Cu-20.4A1-8.7Mn （at.%） at room temperature is investigated by an internal friction technique. Results indicate that the alloy exhibits higher damping capacity in the Ma...The damping capacity of the shape memory alloy Cu-20.4A1-8.7Mn （at.%） at room temperature is investigated by an internal friction technique. Results indicate that the alloy exhibits higher damping capacity in the Martensitic condition than that in the austenitic condition due to the latter having lower intrinsic damping capacity and pinning effect coming from the precipitate particles. The maximum damping capacity is obtained in the coexistence condition of Martensite and austenite. The condition can be achieved when processing an isothermal ageing for the as-cast sample at temperatures of 100 ℃- 150 ℃. Three possible mechanisms are considered to account for the maximum damping capacity. They are listed as much increased interfaces between twin boundaries, owing to the thinning of martensitic plates, martensitic transformation induced by the applied stress during internal friction measurements, phase transformation itself based on the coexistence of martensitic and austenitic phases with a macroscopic amount. However, the contribution of the first mechanism is predominant.展开更多
文摘A new aluminium alloy laminate characterized by high damping, corrosion resistance and weldablity was developed. The laminate designed for required aforesaid functions was actually a composite material, which was made of two anti corrosive layers (Al), two damping layers (ZnAl alloy) and one reinforcing layer (AlMg alloy) by hot rolling. The damping characteristics were studied and it was found that there was an internal friction peak at about 50 ℃ on internal fraction vs temperature curve for the laminate. For this reason, the activation energy of the peak was calculated. The origin and damping mechanism for this peak was researched by means of SEM, TEM, X ray and DSC. It is considered that the peak is caused by the interaction between dislocations and point defects in damping layers (AlZn alloy). i.e. by the movement of dislocations dragging point defects under the action of thermal activation. The laminate is remained at room temperature for a long time, it will weaken or even disappear with the restoration of the crystal microstructure and the reduction of the dislocation density in the ZnAl alloy layers. The mechanism of the peak is in conformity with that of the dislocation induced damping. [
基金Project(51305386)supported by the National Natural Science Foundation of ChinaProject(E2013203093)supported by the Natural Science Foundation of Hebei Province,China
文摘The new forming process of AA6061 alloy tube, including solution treatment, granule medium internal high-pressure forming and aging treatment, was developed. The AA6061 alloy tube via heat treatment satisfied the forming requirement, and the granule medium internal high pressure forming method for AA6061 alloy tube was also realized by using convenient implementation with low requirement of equipment and flexible design of product. At a solution temperature of 560℃ and time of 120 min, the elongation of the AA6061 extruded tube increases by 300% and the strength and the hardness dramatically decrease too. Therefore, the AA6061 alloy tube meets the requirement of internal high-pressure forming because of the improvement of formability. The experiments shows that the strength and hardness of AA6061 alloy workpiece recover to that of the as-received alloy at an aging temperature of 180℃ and time of 360 min, and the strength of AA6061 alloy workpiece is equal to the base alloy. The typical parts of convex ring tube, stepped shaft tube and hexagonal tube were successfully produced in lab by using the present forming method. The forming tests show that the maximum expansion ratio(MER) of the AA6061 extruded tube increases by 25.5% and the material properties of formed AA6061 alloy tube reached the performance of as-received alloy.
文摘Effect of solution treatment temperature on transformations and two way memory, effect in a Ti- 55.2 wt-%Ni alloy was investigated. The results show that with increasing the solution treatment temperature (T_s), two way memory effect (TWME) decreases continuously and temperatures of martensite and reverse, martensite transformations (MR) rise, but the temperature of R start trans- formation (parent→R) does not change. The results of the internal friction measurements indicate that when T_s=1073 K, internal friction peaks of MR and P→R transformations are larger than those of the specimens after solution-treatments at 973 and 1173 K. With increasing T_s, the de- crease of TWME can be attributed to that the defect stress field caused by the rolling fades out grad- ually and preferential martensite variants, which fit into the defect stress field, decrease. The changes of transformation temperatures and internal friction peaks with T_s are closely related to the change of defect numbers.
基金Project supported by the National Natural Science Foundation of China(Grant No.51301150)the Special Program of Science and Technology New Star of Shaanxi Province,China(Grant No.2013KJXX-11)the High-level University Construction Special Program of Shaanxi Province,China(Grant No.Physics-2012SXTS05)
文摘The damping capacity of the shape memory alloy Cu-20.4A1-8.7Mn （at.%） at room temperature is investigated by an internal friction technique. Results indicate that the alloy exhibits higher damping capacity in the Martensitic condition than that in the austenitic condition due to the latter having lower intrinsic damping capacity and pinning effect coming from the precipitate particles. The maximum damping capacity is obtained in the coexistence condition of Martensite and austenite. The condition can be achieved when processing an isothermal ageing for the as-cast sample at temperatures of 100 ℃- 150 ℃. Three possible mechanisms are considered to account for the maximum damping capacity. They are listed as much increased interfaces between twin boundaries, owing to the thinning of martensitic plates, martensitic transformation induced by the applied stress during internal friction measurements, phase transformation itself based on the coexistence of martensitic and austenitic phases with a macroscopic amount. However, the contribution of the first mechanism is predominant.
基金Project(NCET-11-0554)supported by the Program for New Century Excellent Talents in University,ChinaProject(2011BAE22B04)supported by National Key Technology R&D Program of ChinaProject(51271206)supported by the National Natural Science Foundation of China
