The effect of heat treatment on the phase transformation behavior of TiNiCu shape memory alloy wires and the temperature memory effect in this alloy were investigated by the resistance method. These results showed tha...The effect of heat treatment on the phase transformation behavior of TiNiCu shape memory alloy wires and the temperature memory effect in this alloy were investigated by the resistance method. These results showed that with increasing annealing temperature and annealing time, the phase transformation temperatures of TiNiCu wires were shifted to higher temperatures in the heating and cooling process. It was also found that incomplete thermal cycles, upon heating the TiNiCu wires, which were arrested at a temperature between the start and finish temperatures of the reverse martensite transformation, could induce a kinetic stop in the next complete thermal cycle. The kinetic stop temperature was closely related to the previous arrested temperature. This phenomenon was defined as the temperature memory effect. The result of this study was consistent with the previous report on the phenomenon obtained using the differential scanning calorimetry method, indicating that temperature memory effect was a common phenomenon in shape memory alloys.展开更多
Shape memory alloys(SMAs)are well known for their unique shape memory effect(SME)and superelasticity(SE)behavior.The SME and SE have been extensively investigated in past decades due to their potential use in many app...Shape memory alloys(SMAs)are well known for their unique shape memory effect(SME)and superelasticity(SE)behavior.The SME and SE have been extensively investigated in past decades due to their potential use in many applications,especially for smart materials.The unique effects of the SME and SE originate from martensitic transformation and its reverse transformation.Apart from the SME and SE,SMAs also exhibit a unique property of memorizing the point of interruption of martensite to parent phase transformation.If a reverse transformation of a SMA is arrested at a temperature between reverse transformation start temperature(As)and reverse transformation finish temperature(Af),a kinetic stop will appear in the next complete transformation cycle.The kinetic stop temperature is a‘memory’of the previous arrested temperature.This unique phenomenon in SMAs is called temperature memory effect(TME).The TME can be wiped out by heating the SMAs to a temperature higher than Af.The TME is a specific characteristic of the SMAs,which can be observed in TiNi-based and Cu-based alloys.TME can also occur in the R-phase transformation.However,the TME in the R-phase transformation is much weaker than that in the martensite to parent transformation.The decrease of elastic energy after incomplete cycle on heating procedure and the motion of domain walls have significant contributions to the TME.In this paper,the TME in the TiNi-based and Cu-based alloys including wires,slabs and films is characterized by electronic-resistance,elongation and DSC methods.The mechanism of the TME is discussed.展开更多
The microstructure, martensite transformation behavior, thermal stability and shape memory behavior of Ti–20Zr– 10Ta high temperature shape memory alloy were investigated. The Ti–20Zr–10Ta alloy exhibited a revers...The microstructure, martensite transformation behavior, thermal stability and shape memory behavior of Ti–20Zr– 10Ta high temperature shape memory alloy were investigated. The Ti–20Zr–10Ta alloy exhibited a reversible transformation with the high martensite transformation temperature of 500oC and good thermal stability. The alloy displayed the elongation of 15% and a maximum recovery stain of 5.5% with 8% pre-strain.展开更多
文摘The effect of heat treatment on the phase transformation behavior of TiNiCu shape memory alloy wires and the temperature memory effect in this alloy were investigated by the resistance method. These results showed that with increasing annealing temperature and annealing time, the phase transformation temperatures of TiNiCu wires were shifted to higher temperatures in the heating and cooling process. It was also found that incomplete thermal cycles, upon heating the TiNiCu wires, which were arrested at a temperature between the start and finish temperatures of the reverse martensite transformation, could induce a kinetic stop in the next complete thermal cycle. The kinetic stop temperature was closely related to the previous arrested temperature. This phenomenon was defined as the temperature memory effect. The result of this study was consistent with the previous report on the phenomenon obtained using the differential scanning calorimetry method, indicating that temperature memory effect was a common phenomenon in shape memory alloys.
基金supported by the National Natural Science Foundation of China(10704014)the Young Scientists Foundation of Sichuan(09ZQ026-029)and UESTC(JX0731)。
文摘Shape memory alloys(SMAs)are well known for their unique shape memory effect(SME)and superelasticity(SE)behavior.The SME and SE have been extensively investigated in past decades due to their potential use in many applications,especially for smart materials.The unique effects of the SME and SE originate from martensitic transformation and its reverse transformation.Apart from the SME and SE,SMAs also exhibit a unique property of memorizing the point of interruption of martensite to parent phase transformation.If a reverse transformation of a SMA is arrested at a temperature between reverse transformation start temperature(As)and reverse transformation finish temperature(Af),a kinetic stop will appear in the next complete transformation cycle.The kinetic stop temperature is a‘memory’of the previous arrested temperature.This unique phenomenon in SMAs is called temperature memory effect(TME).The TME can be wiped out by heating the SMAs to a temperature higher than Af.The TME is a specific characteristic of the SMAs,which can be observed in TiNi-based and Cu-based alloys.TME can also occur in the R-phase transformation.However,the TME in the R-phase transformation is much weaker than that in the martensite to parent transformation.The decrease of elastic energy after incomplete cycle on heating procedure and the motion of domain walls have significant contributions to the TME.In this paper,the TME in the TiNi-based and Cu-based alloys including wires,slabs and films is characterized by electronic-resistance,elongation and DSC methods.The mechanism of the TME is discussed.
基金Project supported by the National Natural Science Foundation of China （Grant Nos. 51071059 and 51271065） and the National Basic Research Program of China （Grant Nt）. 2012CB619400）
文摘The microstructure, martensite transformation behavior, thermal stability and shape memory behavior of Ti–20Zr– 10Ta high temperature shape memory alloy were investigated. The Ti–20Zr–10Ta alloy exhibited a reversible transformation with the high martensite transformation temperature of 500oC and good thermal stability. The alloy displayed the elongation of 15% and a maximum recovery stain of 5.5% with 8% pre-strain.
