In order to clarify the effect of pt addition on the stress of NiSi film, in situ stress measurements were taken to evaluate the stress evolution during heating and cooling treatment of Ni1- x Ptx Si alloy films with ...In order to clarify the effect of pt addition on the stress of NiSi film, in situ stress measurements were taken to evaluate the stress evolution during heating and cooling treatment of Ni1- x Ptx Si alloy films with different Pt concentrations. The room temperature stress, which is mainly thermal stress, was measured to be 775MPa and 1.31GPa for pure NiSi and pure PtSi films grown on Si (100) substrates,respectively. For Ni1-x Ptx Si alloy film, the room temperature stress was observed to increase steadily with Pt concentration. From the temperature dependent stress evolution curves,the stress relaxation temperature was found to increase from 440℃ (for pure NiSi film) to 620℃ (for pure PtSi film) with increasing Pt concentration, thus influencing the residual stress at room temperature.展开更多
In this study, the long-term thermal microstructural stability and related stress rupture lives of a new Re-containing Ni-based single-crystal superalloy, DD11, were investigated after high-temperature exposure for di...In this study, the long-term thermal microstructural stability and related stress rupture lives of a new Re-containing Ni-based single-crystal superalloy, DD11, were investigated after high-temperature exposure for different lengths of time. The results show that the γ' precipitates retained a cuboidal morphology and the γ' size increased after short thermal exposure for 50 h at 1,070℃. As the thermal exposure time was prolonged to 500 h, the cuboidal γ' gradually changed into irregular raft-like morphology due to particles coalescence, and the morphology of the microstructure was almost unchanged after further thermal exposure up to 3,000 h. The stress rupture experiments at 1,070℃ and a tensile stress of 140 MPa showed that the rupture lives increased significantly after thermal exposure for 50 h and dropped dramatically with increasing exposure time up to 500 h but decreased slowly after exposure for more than 500 h. These results imply that stress rupture properties did not decrease when the γ' remained cuboidal but degraded to different extents during the γ' coarsening process. The coarsening of the γ' precipitates and change in morphology were regarded as the main factors leading to the degradation of the stress rupture lives. This study provides fundamental information on the high-temperature longterm microstructural stability and mechanical performance, which will be of great help for DD11 alloy optimization and engineering aeroengine applications.展开更多
Several effective numerical techniques,based on a finite element analysis,have been developed and computed independently.Results are presented describing the impacting process,and the subsequent temperature and residu...Several effective numerical techniques,based on a finite element analysis,have been developed and computed independently.Results are presented describing the impacting process,and the subsequent temperature and residual stress fields of a molten nickel particle impacting onto a flat substrate.Problems of this type,especially the prediction of the thermal residual stresses,are of major practical interest in thermal spray operations as a pioneering approach.展开更多
The present work has been conducted to study the impact of Zn (20 and 200 μM) or Ni (1 and 100 μM) on growth, metabolic activities, osmotic pressure and heavy metal of wheat cultivar (cv. Gimiza 11) under salt stres...The present work has been conducted to study the impact of Zn (20 and 200 μM) or Ni (1 and 100 μM) on growth, metabolic activities, osmotic pressure and heavy metal of wheat cultivar (cv. Gimiza 11) under salt stress conditions. Harvest index was significantly decreased by 75% at -0.3 MPa and -1.2 MPa decreased by 53%. Length of root, stem and spike, and leaf area were slightly reduced up to -0.9 MPa NaCl level, after that a significant reduction was recorded. Total sugar was increased in the shoot and spike, while decreased in the root with increasing salinity levels. On the other side, total protein was increased in the shoot while decreased in both the root and spike. Osmotic pressure was increased as increasing salinity levels. Treatment of wheat plants with Zn or Ni alleviated generally salt injury in the harvest index, length of root, shoot and spike and leaf area. This effect was more obvious with Zn treatments. Mineralization treatments increased total sugar in the three tested organs while did not change the total protein. Zn content was increased at -1.2 MPa level while Ni was decreased. Treatments with Zn or Ni mostly increased Zn while causing a reduction in the Ni content. These treatments also increased the values of osmotic pressure compared with the equivalent levels of control plants.展开更多
Various training methods for two way memory effect (TWME) and stressed two way memory effect (STWME) were tried on Cu 13.4Al 4.0Ni (mass fraction, %) single crystals by applying tensile stress along 〈001〉 direction ...Various training methods for two way memory effect (TWME) and stressed two way memory effect (STWME) were tried on Cu 13.4Al 4.0Ni (mass fraction, %) single crystals by applying tensile stress along 〈001〉 direction of β phase. The training method of cooling with load can induce a lot of martensite prone to stabilize, thus cause large residual deformation, wide hysteresis and small TWME. Training with constant load can produce STWME larger than 8% with the least residual deformation. By training procedure of martensite reorientation below M f followed by thermal cycling, the TWME is relatively large with very small residual deformation and with comparatively narrow hysteresis of two way memory. The obtained two way memory curve after such training is not a closed loop, and the obtained TWME is not stable. However, these can be improved by thermal cycling. Training with martensite reorientation below M f and thermal cycling under relatively low constant stress throughout the whole training procedure is the optimum way of obtaining TWME, and more than 1.7% TWME can be obtained. The thermomechanical history of the sample has a pronounced effect on the training result. Thermomechanical cycling has a softening effect on martensite. [展开更多
The influence of external field(magnetic field and stress field) on the transformation strain of Ni 52.9- Mn 24.4Ga 22.7 single crystal were investigated and its mechanism was also discussed. When thermally martensiti...The influence of external field(magnetic field and stress field) on the transformation strain of Ni 52.9- Mn 24.4Ga 22.7 single crystal were investigated and its mechanism was also discussed. When thermally martensitic transformation occurs, about 0.25% transformation strain is obtained which may be obviously enhanced to about 0.8% by a 6 000 Oe magnetic bias field. However, the strain decreases by the external compress stress loaded along the strain-measured direction. When the external compress stress and bias magnetic field are simultaneously applied, the transformation strain decreases with increasing the magnetic field, which is related to the rearrangement of the martensite variants influenced by the external field.展开更多
文摘In order to clarify the effect of pt addition on the stress of NiSi film, in situ stress measurements were taken to evaluate the stress evolution during heating and cooling treatment of Ni1- x Ptx Si alloy films with different Pt concentrations. The room temperature stress, which is mainly thermal stress, was measured to be 775MPa and 1.31GPa for pure NiSi and pure PtSi films grown on Si (100) substrates,respectively. For Ni1-x Ptx Si alloy film, the room temperature stress was observed to increase steadily with Pt concentration. From the temperature dependent stress evolution curves,the stress relaxation temperature was found to increase from 440℃ (for pure NiSi film) to 620℃ (for pure PtSi film) with increasing Pt concentration, thus influencing the residual stress at room temperature.
基金funded by the National High Technology Research and Development Program(No.2012AA03A513)
文摘In this study, the long-term thermal microstructural stability and related stress rupture lives of a new Re-containing Ni-based single-crystal superalloy, DD11, were investigated after high-temperature exposure for different lengths of time. The results show that the γ' precipitates retained a cuboidal morphology and the γ' size increased after short thermal exposure for 50 h at 1,070℃. As the thermal exposure time was prolonged to 500 h, the cuboidal γ' gradually changed into irregular raft-like morphology due to particles coalescence, and the morphology of the microstructure was almost unchanged after further thermal exposure up to 3,000 h. The stress rupture experiments at 1,070℃ and a tensile stress of 140 MPa showed that the rupture lives increased significantly after thermal exposure for 50 h and dropped dramatically with increasing exposure time up to 500 h but decreased slowly after exposure for more than 500 h. These results imply that stress rupture properties did not decrease when the γ' remained cuboidal but degraded to different extents during the γ' coarsening process. The coarsening of the γ' precipitates and change in morphology were regarded as the main factors leading to the degradation of the stress rupture lives. This study provides fundamental information on the high-temperature longterm microstructural stability and mechanical performance, which will be of great help for DD11 alloy optimization and engineering aeroengine applications.
文摘Several effective numerical techniques,based on a finite element analysis,have been developed and computed independently.Results are presented describing the impacting process,and the subsequent temperature and residual stress fields of a molten nickel particle impacting onto a flat substrate.Problems of this type,especially the prediction of the thermal residual stresses,are of major practical interest in thermal spray operations as a pioneering approach.
文摘The present work has been conducted to study the impact of Zn (20 and 200 μM) or Ni (1 and 100 μM) on growth, metabolic activities, osmotic pressure and heavy metal of wheat cultivar (cv. Gimiza 11) under salt stress conditions. Harvest index was significantly decreased by 75% at -0.3 MPa and -1.2 MPa decreased by 53%. Length of root, stem and spike, and leaf area were slightly reduced up to -0.9 MPa NaCl level, after that a significant reduction was recorded. Total sugar was increased in the shoot and spike, while decreased in the root with increasing salinity levels. On the other side, total protein was increased in the shoot while decreased in both the root and spike. Osmotic pressure was increased as increasing salinity levels. Treatment of wheat plants with Zn or Ni alleviated generally salt injury in the harvest index, length of root, shoot and spike and leaf area. This effect was more obvious with Zn treatments. Mineralization treatments increased total sugar in the three tested organs while did not change the total protein. Zn content was increased at -1.2 MPa level while Ni was decreased. Treatments with Zn or Ni mostly increased Zn while causing a reduction in the Ni content. These treatments also increased the values of osmotic pressure compared with the equivalent levels of control plants.
文摘Various training methods for two way memory effect (TWME) and stressed two way memory effect (STWME) were tried on Cu 13.4Al 4.0Ni (mass fraction, %) single crystals by applying tensile stress along 〈001〉 direction of β phase. The training method of cooling with load can induce a lot of martensite prone to stabilize, thus cause large residual deformation, wide hysteresis and small TWME. Training with constant load can produce STWME larger than 8% with the least residual deformation. By training procedure of martensite reorientation below M f followed by thermal cycling, the TWME is relatively large with very small residual deformation and with comparatively narrow hysteresis of two way memory. The obtained two way memory curve after such training is not a closed loop, and the obtained TWME is not stable. However, these can be improved by thermal cycling. Training with martensite reorientation below M f and thermal cycling under relatively low constant stress throughout the whole training procedure is the optimum way of obtaining TWME, and more than 1.7% TWME can be obtained. The thermomechanical history of the sample has a pronounced effect on the training result. Thermomechanical cycling has a softening effect on martensite. [
文摘The influence of external field(magnetic field and stress field) on the transformation strain of Ni 52.9- Mn 24.4Ga 22.7 single crystal were investigated and its mechanism was also discussed. When thermally martensitic transformation occurs, about 0.25% transformation strain is obtained which may be obviously enhanced to about 0.8% by a 6 000 Oe magnetic bias field. However, the strain decreases by the external compress stress loaded along the strain-measured direction. When the external compress stress and bias magnetic field are simultaneously applied, the transformation strain decreases with increasing the magnetic field, which is related to the rearrangement of the martensite variants influenced by the external field.