By applying tensile stress along 〈100〉 of β phase, the superelastic behavior and stabilization of stress induced martensite (SIM) of Cu 13.4Al 4.0Ni(mass fraction, %) single crystals were studied. The results show ...By applying tensile stress along 〈100〉 of β phase, the superelastic behavior and stabilization of stress induced martensite (SIM) of Cu 13.4Al 4.0Ni(mass fraction, %) single crystals were studied. The results show that the pseudo yield stress decreases with the increase of cycling number, and keeping load isothermally has an effect on stabilization of SIM. Previous thermal cycling between ( M s-20 ℃) and ( A f+20 ℃) promotes the superelasticity and the stabilization of SIM as well; the pre thermal cycling also reduces the pseudo yield stress. However, once the stabilization of SIM is produced, it can be destabilized by either the afterwards thermal cooling heating cycling or load and immediately unload cycling in ( A f～ M d). Isothermal treatment in ( A f～ M d) brings restabilization of SIM. The maximum superelastic value from β → β ′ 1(18 R ) is 9% for the studied single crystal. When test temperature is in A f～( A f+50 ℃) and stress is in 0～350 MPa, the superelastic behavior exist. [展开更多
The deformation behavior ofβ-quenched nearβTi-5321(Ti-5Al-3Mo-3V-2Cr-2Zr-1Nb-1Fe)alloy was systematically studied using in-situ tensile test monitored by the scanning electron microscopy(SEM).Besides,the electron ba...The deformation behavior ofβ-quenched nearβTi-5321(Ti-5Al-3Mo-3V-2Cr-2Zr-1Nb-1Fe)alloy was systematically studied using in-situ tensile test monitored by the scanning electron microscopy(SEM).Besides,the electron backscatter diffraction(EBSD)was performed to thoroughly discuss the deformation mechanisms.The results indicated that slip activities,crystal rotation and stress induced martensite transformation were the major deformation mechanisms in theβ-quenched Ti-5321 alloy during in-situ tensile testing.The slip activities were investigated by using the EBSD-trace analysis,which demonstrated that{110}<111>,{112}<111>and{123}<111>slip systems were activated and the{110}<111>slip system dominated.Besides,βgrains rotated about 7.8°to accommodate the increased macrostrain.Notably,the stress induced martensiteα″which was related to the double yielding behavior during tensile process exhibited multiple characteristics.The differentα″variants divided theβmatrix into smallerβblocks with a typical zigzag morphology,in which oneα″variant passed through another one by deflecting its initial growth direction.Moreover,the deformation twinning in martensiteα″and slip bands cutting through martensiteα″effectively accommodated the local strain.These systematically analysis can provide insightful information about the deformation mechanisms in nearβtitanium alloys.展开更多
A possible mechanism of all-round shape memory behaviour hy help of a physical model pro- posed by Muller has been ascertained.The all-round shape mernory effect can be due to the fact that stress induced martensite o...A possible mechanism of all-round shape memory behaviour hy help of a physical model pro- posed by Muller has been ascertained.The all-round shape mernory effect can be due to the fact that stress induced martensite of two different orientations is formed during the martensitic transformation in the outer and inner layers of the specimen respectively.展开更多
文摘By applying tensile stress along 〈100〉 of β phase, the superelastic behavior and stabilization of stress induced martensite (SIM) of Cu 13.4Al 4.0Ni(mass fraction, %) single crystals were studied. The results show that the pseudo yield stress decreases with the increase of cycling number, and keeping load isothermally has an effect on stabilization of SIM. Previous thermal cycling between ( M s-20 ℃) and ( A f+20 ℃) promotes the superelasticity and the stabilization of SIM as well; the pre thermal cycling also reduces the pseudo yield stress. However, once the stabilization of SIM is produced, it can be destabilized by either the afterwards thermal cooling heating cycling or load and immediately unload cycling in ( A f～ M d). Isothermal treatment in ( A f～ M d) brings restabilization of SIM. The maximum superelastic value from β → β ′ 1(18 R ) is 9% for the studied single crystal. When test temperature is in A f～( A f+50 ℃) and stress is in 0～350 MPa, the superelastic behavior exist. [
基金financially supported by the National International Science and Technology Cooperation Project of China(No.2015DF151430)。
文摘The deformation behavior ofβ-quenched nearβTi-5321(Ti-5Al-3Mo-3V-2Cr-2Zr-1Nb-1Fe)alloy was systematically studied using in-situ tensile test monitored by the scanning electron microscopy(SEM).Besides,the electron backscatter diffraction(EBSD)was performed to thoroughly discuss the deformation mechanisms.The results indicated that slip activities,crystal rotation and stress induced martensite transformation were the major deformation mechanisms in theβ-quenched Ti-5321 alloy during in-situ tensile testing.The slip activities were investigated by using the EBSD-trace analysis,which demonstrated that{110}<111>,{112}<111>and{123}<111>slip systems were activated and the{110}<111>slip system dominated.Besides,βgrains rotated about 7.8°to accommodate the increased macrostrain.Notably,the stress induced martensiteα″which was related to the double yielding behavior during tensile process exhibited multiple characteristics.The differentα″variants divided theβmatrix into smallerβblocks with a typical zigzag morphology,in which oneα″variant passed through another one by deflecting its initial growth direction.Moreover,the deformation twinning in martensiteα″and slip bands cutting through martensiteα″effectively accommodated the local strain.These systematically analysis can provide insightful information about the deformation mechanisms in nearβtitanium alloys.
文摘A possible mechanism of all-round shape memory behaviour hy help of a physical model pro- posed by Muller has been ascertained.The all-round shape mernory effect can be due to the fact that stress induced martensite of two different orientations is formed during the martensitic transformation in the outer and inner layers of the specimen respectively.
