Static mechanical experiments were carried out on granite after and under different temperatures using an electro-hydraulic and servo-controlled material testing machine with a heating device. Variations in obvious fo...Static mechanical experiments were carried out on granite after and under different temperatures using an electro-hydraulic and servo-controlled material testing machine with a heating device. Variations in obvious form, stress-strain curve, peak strength, peak strain and elastic modulus with temperature were analyzed and the essence of rock failure modes was explored. The results indicate that, compared with granite after the high temperature treatment, the brittle-ductile transition critical temperature is lower, the densification stage is longer, the elastic modulus is smaller and the damage is larger under high temperature. In addition, the peak stress is lower and the peak strain is greater, but both of them change more obviously with the increase of temperature compared with that of granite after the high temperature treatment. Furthermore, the failure modes of granite after the high temperature treatment and under high temperature show a remarkable difference. Below 100 ℃, the failure modes of granite under both conditions are the same, presenting splitting failure. However, after 100 ℃, the failure modes of granite after the high temperature treatment and under high temperature present splitting failure and shear failure, respectively.展开更多
The structural and thermodynamic properties of Zr2A1C at high pressure and high temper- ature are investigated by first principles density functional theory method. The calculated lattice parameters of Zr2A1C are in g...The structural and thermodynamic properties of Zr2A1C at high pressure and high temper- ature are investigated by first principles density functional theory method. The calculated lattice parameters of Zr2A1C are in good agreement with the available theoretical data. The pressure dependences of the elastic constants, bulk modulus, shear modulus, Young＇s mod- ulus, and Vickers hardness of Zr2A1C are successfully obtained. The elastic anisotropy is examined through the computation of the direction dependence of Young＇s modulus. By using the quasiharmonic Debye model, the thermodynamic properties including the Debye temperature, heat capacity, volume thermal expansion coefficient, and Griineisen parameter at high pressure and temperature are predicted for the first time.展开更多
The Ti Bw reinforced near-α titanium matrix composite（Ti-5.8 Al-3.4 Zr-4.0 Sn-0.4 Mo-0.4 Nb-0.4 Si-0.06 C） was successfully synthesized by powder metallurgy and hot extrusion route. The effects of solution and agin...The Ti Bw reinforced near-α titanium matrix composite（Ti-5.8 Al-3.4 Zr-4.0 Sn-0.4 Mo-0.4 Nb-0.4 Si-0.06 C） was successfully synthesized by powder metallurgy and hot extrusion route. The effects of solution and aging temperature on the microstructure and high temperature tensile properties of the composite were investigated. The results revealed that the fine transformed β phase can be obtained by the solution treatment at β phase region and aging treatment, no other precipitates were observed. The α2 phase（Ti3 Al） can be acquired when the solution treated at α＋β phase region followed by aging treatment. With increasing the aging temperature from 500 to 700℃ for 5 h, the size of α2 precipitates increases from about 5 to about 30 nm. The Ti Bw are stable without any interfacial reaction during the heat treatments. The high temperature tensile properties show that the composite performed by solution and aging treatment exhibits good strengthening effects. With increasing the aging temperature from 500 to 700℃, the strength of the composite increases at the expense of elongation due to the increment of α2 precipitates.The strength of the composite at 600℃ increases by 17% to 986 MPa after 1000℃/2 h/AC and 700℃/5 h/AC heat treatment.展开更多
Shock relations usually found in literatures are derived theoretically under the assumption of homogeneous thermodynamic properties, i.e., constant ratio of specific heats, γ. However, high temperature effects post a...Shock relations usually found in literatures are derived theoretically under the assumption of homogeneous thermodynamic properties, i.e., constant ratio of specific heats, γ. However, high temperature effects post a strong shock wave may result in thermodynamic heterogeneities and failure to the original shock relations. In this paper, the shock relations are extended to take account of high-temperature effects. Comparison indicates that the present approach is more feasible than other analytical approaches to reflect the influence of γ heterogeneity on the post-shock parameters.展开更多
基金Projects(51304241,11472311,51322403)supported by the National Natural Science Foundation of ChinaProject(2015CX005)supported by Innovation Driven Plan of Central South University,China+1 种基金Project(2016zzts456)supported by Independent Exploration and Innovation Foundation of Central South University,ChinaProject(2015CB060200)supported by the National Basic Research Program of China
文摘Static mechanical experiments were carried out on granite after and under different temperatures using an electro-hydraulic and servo-controlled material testing machine with a heating device. Variations in obvious form, stress-strain curve, peak strength, peak strain and elastic modulus with temperature were analyzed and the essence of rock failure modes was explored. The results indicate that, compared with granite after the high temperature treatment, the brittle-ductile transition critical temperature is lower, the densification stage is longer, the elastic modulus is smaller and the damage is larger under high temperature. In addition, the peak stress is lower and the peak strain is greater, but both of them change more obviously with the increase of temperature compared with that of granite after the high temperature treatment. Furthermore, the failure modes of granite after the high temperature treatment and under high temperature show a remarkable difference. Below 100 ℃, the failure modes of granite under both conditions are the same, presenting splitting failure. However, after 100 ℃, the failure modes of granite after the high temperature treatment and under high temperature present splitting failure and shear failure, respectively.
基金This work was supportted by the National Natural Science Foundation of China （No.11447176 and No.11447152）, the National Natural Science Foundation of China and the China Academy of Engineering Physics （No.U1230201）, and the Doctor Foundation of Southwest University of Science and Technology （No.13zx7137 and No.14zx7167）.
文摘The structural and thermodynamic properties of Zr2A1C at high pressure and high temper- ature are investigated by first principles density functional theory method. The calculated lattice parameters of Zr2A1C are in good agreement with the available theoretical data. The pressure dependences of the elastic constants, bulk modulus, shear modulus, Young＇s mod- ulus, and Vickers hardness of Zr2A1C are successfully obtained. The elastic anisotropy is examined through the computation of the direction dependence of Young＇s modulus. By using the quasiharmonic Debye model, the thermodynamic properties including the Debye temperature, heat capacity, volume thermal expansion coefficient, and Griineisen parameter at high pressure and temperature are predicted for the first time.
基金supported by the National Natural Science Foundation of China(Grant Nos.51701114,11604204,51471063,51271111)the Youth Teacher Development Program of Shanghai Universities(Grant No.ZZGCD15101)+1 种基金Scientific Research Project of Shanghai University of Engineering ScienceTalents Project of Shanghai University of Engineering Science
文摘The Ti Bw reinforced near-α titanium matrix composite（Ti-5.8 Al-3.4 Zr-4.0 Sn-0.4 Mo-0.4 Nb-0.4 Si-0.06 C） was successfully synthesized by powder metallurgy and hot extrusion route. The effects of solution and aging temperature on the microstructure and high temperature tensile properties of the composite were investigated. The results revealed that the fine transformed β phase can be obtained by the solution treatment at β phase region and aging treatment, no other precipitates were observed. The α2 phase（Ti3 Al） can be acquired when the solution treated at α＋β phase region followed by aging treatment. With increasing the aging temperature from 500 to 700℃ for 5 h, the size of α2 precipitates increases from about 5 to about 30 nm. The Ti Bw are stable without any interfacial reaction during the heat treatments. The high temperature tensile properties show that the composite performed by solution and aging treatment exhibits good strengthening effects. With increasing the aging temperature from 500 to 700℃, the strength of the composite increases at the expense of elongation due to the increment of α2 precipitates.The strength of the composite at 600℃ increases by 17% to 986 MPa after 1000℃/2 h/AC and 700℃/5 h/AC heat treatment.
基金supported by the National Natural Science Foundation of China(Grant Nos.11672308 and 11532014)Innovation Grant of Chinese Academy of Sciences
文摘Shock relations usually found in literatures are derived theoretically under the assumption of homogeneous thermodynamic properties, i.e., constant ratio of specific heats, γ. However, high temperature effects post a strong shock wave may result in thermodynamic heterogeneities and failure to the original shock relations. In this paper, the shock relations are extended to take account of high-temperature effects. Comparison indicates that the present approach is more feasible than other analytical approaches to reflect the influence of γ heterogeneity on the post-shock parameters.
