Nanoporous copper with nano-scale pore size was synthesized by dealloying Mn-Cu precursor alloy using a free corrosion method.The effects of heat treatment of Mn-Cu precursors on alloy phase,morphology and composition...Nanoporous copper with nano-scale pore size was synthesized by dealloying Mn-Cu precursor alloy using a free corrosion method.The effects of heat treatment of Mn-Cu precursors on alloy phase,morphology and composition of the resultant nanoporous copper were investigated.It is revealed that the compositions distribute homogeneously in the bulk Mn-Cu precursors,which consequently results in a more fully dealloying for forming nanoporous copper.The alloy phase changes from Cu0.49Mn0.51 and Cu0.21Mn0.79 of non-thermally treated precursor to Cu0.33Mn0.67 of heat treated alloy.The residual Mn content in nanoporous copper is decreased from 12.97% to 2.04%(molar fraction) made from the precursor without and with 95 h heat treatment.The typical pore shape of nanoporous copper prepared by dealloying the precursor without the heat treatment is divided into two different zones:the uniform bi-continuous structure zone and the blurry or no pore structure zone.Nanoporous copper is of a uniform sponge-like morphology made from the heat-treated precursor,and the average ligament diameter is 40 nm,far smaller than that from the non-thermally treated precursor,in which the average ligament diameter is estimated to be about 70 nm.展开更多
The stress–strain behavior and strain rate sensitivity of pre-strained Ni80Cr20（Ni20Cr） were studied at strain rates from 4.8×10^（–4）s^（–1） to 1.1×10^（–1）s^（–1）. Specimens were prepared throug...The stress–strain behavior and strain rate sensitivity of pre-strained Ni80Cr20（Ni20Cr） were studied at strain rates from 4.8×10^（–4）s^（–1） to 1.1×10^（–1）s^（–1）. Specimens were prepared through cold drawing with abnormal plastic deformation. The texture of the specimen was characterized using electron backscatter diffraction. Results revealed that the ultimate tensile strength and ductility of the pre-strained Ni20Cr microwires simultaneously increased with increasing strain rate. Twinning-induced negative strain rate sensitivity was discovered. Positive strain rate sensitivity was present in fracture flow stress, whereas negative strain rate sensitivity was detected in flow stress values of σ_（0.5%） and σ_（1%）. Tensile test of the pre-strained Ni20Cr showed that twinning deformation predominated, whereas dislocation slip deformation dominated when twinning deformation reached saturation. The trends observed in the fractions of 2°-5°, 5°-15°, and 15°-180° grain boundaries confirmed that twinning deformation dominated the first stage.展开更多
基金Project(10804101) supported by the National Natural Science Foundation of ChinaProject(9140C6805021008) supported by the State Key Development Program for Basic Research of ChinaProject(2007B08007) supported by the Science and Technology Development Foundation of Chinese Academy of Engineering Physics
文摘Nanoporous copper with nano-scale pore size was synthesized by dealloying Mn-Cu precursor alloy using a free corrosion method.The effects of heat treatment of Mn-Cu precursors on alloy phase,morphology and composition of the resultant nanoporous copper were investigated.It is revealed that the compositions distribute homogeneously in the bulk Mn-Cu precursors,which consequently results in a more fully dealloying for forming nanoporous copper.The alloy phase changes from Cu0.49Mn0.51 and Cu0.21Mn0.79 of non-thermally treated precursor to Cu0.33Mn0.67 of heat treated alloy.The residual Mn content in nanoporous copper is decreased from 12.97% to 2.04%(molar fraction) made from the precursor without and with 95 h heat treatment.The typical pore shape of nanoporous copper prepared by dealloying the precursor without the heat treatment is divided into two different zones:the uniform bi-continuous structure zone and the blurry or no pore structure zone.Nanoporous copper is of a uniform sponge-like morphology made from the heat-treated precursor,and the average ligament diameter is 40 nm,far smaller than that from the non-thermally treated precursor,in which the average ligament diameter is estimated to be about 70 nm.
基金Funded by the National Natural Science Foundation of China(No.11135007)
文摘The stress–strain behavior and strain rate sensitivity of pre-strained Ni80Cr20（Ni20Cr） were studied at strain rates from 4.8×10^（–4）s^（–1） to 1.1×10^（–1）s^（–1）. Specimens were prepared through cold drawing with abnormal plastic deformation. The texture of the specimen was characterized using electron backscatter diffraction. Results revealed that the ultimate tensile strength and ductility of the pre-strained Ni20Cr microwires simultaneously increased with increasing strain rate. Twinning-induced negative strain rate sensitivity was discovered. Positive strain rate sensitivity was present in fracture flow stress, whereas negative strain rate sensitivity was detected in flow stress values of σ_（0.5%） and σ_（1%）. Tensile test of the pre-strained Ni20Cr showed that twinning deformation predominated, whereas dislocation slip deformation dominated when twinning deformation reached saturation. The trends observed in the fractions of 2°-5°, 5°-15°, and 15°-180° grain boundaries confirmed that twinning deformation dominated the first stage.
