We present observations of martensite variants and ferromagnetic domain structures of Ni_(53)Mn_(24)Ga_(23) ferromagnetic shape memory alloys with a pure tetragonal martensitic phase by using scanning electron aconsti...We present observations of martensite variants and ferromagnetic domain structures of Ni_(53)Mn_(24)Ga_(23) ferromagnetic shape memory alloys with a pure tetragonal martensitic phase by using scanning electron aconstic microscopy (SEAM) and scanning thermal microscopy (SThM).Electron acoustic images show a polycrystalline morphology with martensite variants.Direct coincidence between crystallographic martensitic twin variants and magnetic domains is found.A domain-like structure,obtained by SThM,is firstly reported,and then confirmed by magnetic force microscopy (MFM).The experimental results will be helpful for investigating the local thermal properties of ferromagnets and understanding the relationship between martensite variants and magnetic domains.展开更多
Bismuth zinc titanate dopied lead magnesium niobate-lead titanate[Bi(Zn_(1/2)Ti_(1/2))O_(3)−Pb(Mg_(1/3)Nb_(2/3))O_(3)−PbTiO_(3)(BZT-PMN-PT)]piezoelectric ceramics are synthesized by the conventional solid state reacti...Bismuth zinc titanate dopied lead magnesium niobate-lead titanate[Bi(Zn_(1/2)Ti_(1/2))O_(3)−Pb(Mg_(1/3)Nb_(2/3))O_(3)−PbTiO_(3)(BZT-PMN-PT)]piezoelectric ceramics are synthesized by the conventional solid state reaction method.Ferroelectric domain structures and the evolutionary behavior of BZT-PMN-PT ceramics under an external in-plane electric field are investigated by piezoresponse force microscopy(PFM).It is found that the BZT doping has a significant effect on the domain configurations and the domain kinetic behavior of the piezoelectric BZT-PMN-PT solid solution ceramics.Microdomains embedded in the macrodomains,induced by the BZT dopant in the solid solution ceramics,are clearly observed by PFM and their volume increases with increasing amounts of BZT doping.The microdomains of BZT-PMN-PT piezoelectric ceramics exhibit better domain dynamic behavior stability than macrodomains under an external in-plane electric field.展开更多
The microstructures and mechanical properties of Cr13 super martensitic stainless steel after different heat treatments were studied. The results show that the structures of the steel after quenching are of lath marte...The microstructures and mechanical properties of Cr13 super martensitic stainless steel after different heat treatments were studied. The results show that the structures of the steel after quenching are of lath martensite mixed with a small amount of retained austenite. With the raising quenching temperature, the original austenite grain size increases and the lath martensite gradually becomes thicker. The structures of the tempered steel are mixtures of tempered martensite and reversed austenite dispersed in the martensite matrix. The amount of reversed austenite is from 7.54% to 22. 49%. After different heat treatments, the tensile strength, the elongation and the HRC hardness of the steel are in the range of 813 1 070 MPa, 10.1%--21.2% and 21.33--32.37, respectively. The steel displays the best comprehensive mechanical properties after the sample is quenched at 1 050 ℃ followed by tempering at 650 ℃.展开更多
The effect of different heat treatments on the reversed austenite in Cr15 super martensitic stainless steel was investigated. The experimental results indicate that the microstructure of the steel is composed of tempe...The effect of different heat treatments on the reversed austenite in Cr15 super martensitic stainless steel was investigated. The experimental results indicate that the microstructure of the steel is composed of tempered martensite and diffused reversed austenite after quenching at 1 050 ℃ and tempering from 550 to 750 ℃. The volume fraction and size of reversed austenite increase with increasing tempering temperature and both of them reach the maximum value at 700 ℃. The volume fraction and size of reversed austenite decrease when the temperature is above 700 ℃. The transmission electron microscope （TEM） results indicate that the orientation relationship between tempered martensite and reversed austenite belongs to Kurdjmov-Sach （K-S） relationship.展开更多
The effects of chloride ion on the electrochemical behavior and the semiconducting properties of the passive film on supermartensitic stainless steel in 0.5 mol/L NaHCO_3 solution were investigated using potentiodynam...The effects of chloride ion on the electrochemical behavior and the semiconducting properties of the passive film on supermartensitic stainless steel in 0.5 mol/L NaHCO_3 solution were investigated using potentiodynamic polarization, the potentiostatic current transients and Mott-Schottky analysis. The results indicated that chloride ion narrowed passivation region and improved pitting susceptibility. The steady state current densities were independent of film-formed potentials, which was in good agreement with the assumption of the point defect model （PDM）. The capacitance results showed the fact that the passive films had a multilayer character. The defect density decreased with increasing passive film formation potential. The chloride ion induced changes of the acceptor densities and donor densities of the passive films.展开更多
基金Supported by the National Basic Research Program of China under Grant Nos 2012CB933004 and 2009CB623305the Innovative Research Groups of the National Natural Science Foundation of China under Grant No 51121064+1 种基金the Nanotechnology Project of Shanghai Science and Technology Committee(No 11nm0502800)the Innovation Project of the Shanghai Institute of Ceramics(Y21ZC4110G).
文摘We present observations of martensite variants and ferromagnetic domain structures of Ni_(53)Mn_(24)Ga_(23) ferromagnetic shape memory alloys with a pure tetragonal martensitic phase by using scanning electron aconstic microscopy (SEAM) and scanning thermal microscopy (SThM).Electron acoustic images show a polycrystalline morphology with martensite variants.Direct coincidence between crystallographic martensitic twin variants and magnetic domains is found.A domain-like structure,obtained by SThM,is firstly reported,and then confirmed by magnetic force microscopy (MFM).The experimental results will be helpful for investigating the local thermal properties of ferromagnets and understanding the relationship between martensite variants and magnetic domains.
基金by the Foundation for Innovative Research Groups of the National Natural Science Foundation of China under Grant No 50821004the National Basic Research Program of China under Grant No 2009CB623305the Project-Sponsored by SRF for ROCS,SEM,China.
文摘Bismuth zinc titanate dopied lead magnesium niobate-lead titanate[Bi(Zn_(1/2)Ti_(1/2))O_(3)−Pb(Mg_(1/3)Nb_(2/3))O_(3)−PbTiO_(3)(BZT-PMN-PT)]piezoelectric ceramics are synthesized by the conventional solid state reaction method.Ferroelectric domain structures and the evolutionary behavior of BZT-PMN-PT ceramics under an external in-plane electric field are investigated by piezoresponse force microscopy(PFM).It is found that the BZT doping has a significant effect on the domain configurations and the domain kinetic behavior of the piezoelectric BZT-PMN-PT solid solution ceramics.Microdomains embedded in the macrodomains,induced by the BZT dopant in the solid solution ceramics,are clearly observed by PFM and their volume increases with increasing amounts of BZT doping.The microdomains of BZT-PMN-PT piezoelectric ceramics exhibit better domain dynamic behavior stability than macrodomains under an external in-plane electric field.
文摘The microstructures and mechanical properties of Cr13 super martensitic stainless steel after different heat treatments were studied. The results show that the structures of the steel after quenching are of lath martensite mixed with a small amount of retained austenite. With the raising quenching temperature, the original austenite grain size increases and the lath martensite gradually becomes thicker. The structures of the tempered steel are mixtures of tempered martensite and reversed austenite dispersed in the martensite matrix. The amount of reversed austenite is from 7.54% to 22. 49%. After different heat treatments, the tensile strength, the elongation and the HRC hardness of the steel are in the range of 813 1 070 MPa, 10.1%--21.2% and 21.33--32.37, respectively. The steel displays the best comprehensive mechanical properties after the sample is quenched at 1 050 ℃ followed by tempering at 650 ℃.
文摘The effect of different heat treatments on the reversed austenite in Cr15 super martensitic stainless steel was investigated. The experimental results indicate that the microstructure of the steel is composed of tempered martensite and diffused reversed austenite after quenching at 1 050 ℃ and tempering from 550 to 750 ℃. The volume fraction and size of reversed austenite increase with increasing tempering temperature and both of them reach the maximum value at 700 ℃. The volume fraction and size of reversed austenite decrease when the temperature is above 700 ℃. The transmission electron microscope （TEM） results indicate that the orientation relationship between tempered martensite and reversed austenite belongs to Kurdjmov-Sach （K-S） relationship.
文摘The effects of chloride ion on the electrochemical behavior and the semiconducting properties of the passive film on supermartensitic stainless steel in 0.5 mol/L NaHCO_3 solution were investigated using potentiodynamic polarization, the potentiostatic current transients and Mott-Schottky analysis. The results indicated that chloride ion narrowed passivation region and improved pitting susceptibility. The steady state current densities were independent of film-formed potentials, which was in good agreement with the assumption of the point defect model （PDM）. The capacitance results showed the fact that the passive films had a multilayer character. The defect density decreased with increasing passive film formation potential. The chloride ion induced changes of the acceptor densities and donor densities of the passive films.
