The effects of Ti element on the corrosion resistance of the metallic glass Zr51.3AlloNi6Cu31.8Ag0.lY0.8 in aqueous solution with various chloride concentrations were investigated, and the effect mechanism was discuss...The effects of Ti element on the corrosion resistance of the metallic glass Zr51.3AlloNi6Cu31.8Ag0.lY0.8 in aqueous solution with various chloride concentrations were investigated, and the effect mechanism was discussed. X-ray diffraction con-firmed that Ti-added Zr51.3All0Ni6Cu31.8Ag0.lY0.8 metallic glasses with diameter of 3 mm were all metallic glasses. Weight loss and electrochemical method were introduced to characterize their corrosion resistance, and X-ray photo-electron spectroscopy study was used t9 characterize the passive film composition. The results show that the corrosion resistance of metallic glass is significantly improved with Ti addition, and Zr dioxides dominate in passive film during corrosion when Ti content is low. High Ti addition can lead to an obvious accumulation of Ti dioxides, which results in a thicker, Ti-enriched protective passive film.展开更多
Two Ni/Ni3Al-interface-contained cluster models with/without lattice misfit are studied by first-principles method to clarify the debates about the segregation behaviors of Hafnium （Hf） and explore the influence of ...Two Ni/Ni3Al-interface-contained cluster models with/without lattice misfit are studied by first-principles method to clarify the debates about the segregation behaviors of Hafnium （Hf） and explore the influence of lattice misfit on the ductility effect of Hr. It is found that though Hf prefers to substitute A1 rather than Ni in Ni3A1 phase within most of the investigated misfit range, its stronger preferring to Ni phase than NiaA1 phase makes it impossible to go into Ni3A1 phase to occupy A1 site in Ni-Ni3A1 alloys. Bond order analysis in Hf-free case shows that lattice misfit has different effects on the Griffith work of interfacial cleavage 27int/E and the maximum theoretical shear stress Zmax of Ni and Ni3A1, contributing to the existence of anomalous strength-temperature phenomena in NiaA1 alloys. However, the addition of Hf will make the 27int/E （or Zmax） of both Ni3A1 and Ni decrease （or increase） with lattice misfit, indicating that the addition of Hf may make the anomalous strength-temperature relationship in Ni3A1 region disappear locally.展开更多
The interfacial oxidation behavior of Cr_(4)Mo_(4) V high-speed steel(HSS)joints undergoing hot-compression bonding was investigated by using optical microscopy(OM),scanning electron microscopy(SEM),and transmission e...The interfacial oxidation behavior of Cr_(4)Mo_(4) V high-speed steel(HSS)joints undergoing hot-compression bonding was investigated by using optical microscopy(OM),scanning electron microscopy(SEM),and transmission electron microscopy(TEM).In the heating and holding processes,dispersed rod-like and granularδ-Al_(2)O_(3) oxides were formed at the interface and in the matrix near the interface due to the selective oxidation and internal oxidation of Al,while irregular Si-Al-O compounds and spheroidal SiO_(2) particles were formed at the interface.After the post-holding treatment,SiO_(2) oxides and Si-Al-O compounds were dissolved into the matrix,andδ-Al_(2)O_(3) oxides were transformed into nanoscaleα-Al_(2)O_(3) particles,which did not deteriorate the mechanical properties of the joints.The formation and migration of newly-formed grain boundaries by plastic deformation and post-holding treatment were the main mechanism for interface healing.The tensile test results showed that the strength of the healed joints was comparable to that of the base material,and the in-situ tensile observations proved that the fracture was initiated at the grain boundary of the matrix rather than at the interface.The clarification of interfacial oxides and microstructure is essential for the application of hot-compression bonding of HSSs.展开更多
Nanoporous metals have attracted signifi cant attention owing to their excellent physical,chemical,and biological properties.However,preparing ultrafi ne nanoporous metal particles(1–5μm)with specifi c geometries re...Nanoporous metals have attracted signifi cant attention owing to their excellent physical,chemical,and biological properties.However,preparing ultrafi ne nanoporous metal particles(1–5μm)with specifi c geometries remains challenging.Herein,we report a simple strategy to prepare ultrafi ne fl aky hexagonal nanoporous Au-Cu and Au particles via dealloying.Mg-based alloy ribbons with ultrafi ne fl aky hexagonal Mg-Au(Cu)-Gd particles dispersed in a Mg-Cu(Au)-Gd metallic glassy matrix were prepared.The size and morphology of the precipitated fl aky hexagonal Mg-Au(Cu)-Gd particles were controlled by the solidifi cation process of a Mg 61 Cu 21 Au 7 Gd 11 alloy melt.Ultrafi ne fl aky hexagonal nanoporous Au-Cu particles(diagonal diameter 2.58±0.44μm,ligament size~28 nm),Au-1 particles(diagonal diameter 2.38±0.35μm,ligament size~83 nm)and Au-2 particles(diagonal diameter 2.39±0.44μm,ligament size~66 nm)were prepared via ultrasonic-assisted dealloying of Mg 61 Cu 21 Au 7 Gd 11 alloy ribbons in 0.25 M HCl/ethanol,1 M HCl/ethanol and 0.25 M HNO 3/ethanol solutions,respectively.The ultrafi ne fl aky hexagonal nanoporous Au-Cu and Au particles with a large specifi c surface area have a uniform particle size and shape,implying that they possess adequate powder fl uidity and excellent catalytic properties.Moreover,the formation mechanism of the MgAu(Cu)Gd phase in solidifi ed Mg-Cu-Au-Gd alloys was discussed.This study provides a novel approach for synthesizing nanoporous metal particles with a specifi c geometry.展开更多
基金This work is supported by the National Natural Science Foundation of China [51434008 （U1435204）, 51531005], China＇s Manned Space Station Project （Mission No. TGJZ800-2-RW024）, CAS Key Project ＂Research ＆ Development of Nuclear Materials and Service Safety Assurance Technology＂ （ZDRW-CN- 2017-1 ）, DongGuan Innovative Research Team Program （2014607134）, Shenyang Key R＆D and Technology Transfer Pro-gram （Z17-7-001）, Theme Special Project of Shenyang Key Science and Technology Research and Development Programs （17-85-0-00）, and Double-hundred Program of Shenyang Science and Technology Innovation Project （Y17-2-036）.
文摘The effects of Ti element on the corrosion resistance of the metallic glass Zr51.3AlloNi6Cu31.8Ag0.lY0.8 in aqueous solution with various chloride concentrations were investigated, and the effect mechanism was discussed. X-ray diffraction con-firmed that Ti-added Zr51.3All0Ni6Cu31.8Ag0.lY0.8 metallic glasses with diameter of 3 mm were all metallic glasses. Weight loss and electrochemical method were introduced to characterize their corrosion resistance, and X-ray photo-electron spectroscopy study was used t9 characterize the passive film composition. The results show that the corrosion resistance of metallic glass is significantly improved with Ti addition, and Zr dioxides dominate in passive film during corrosion when Ti content is low. High Ti addition can lead to an obvious accumulation of Ti dioxides, which results in a thicker, Ti-enriched protective passive film.
基金Acknowledgments The authors acknowledge the financial support from the National Natural Science Foundation of China （Nos. 51001001 and 51201002）. Prof. Y.M. Wang and Dr. H. Li are kindly thanked for helpful discussion and proof reading.
文摘Two Ni/Ni3Al-interface-contained cluster models with/without lattice misfit are studied by first-principles method to clarify the debates about the segregation behaviors of Hafnium （Hf） and explore the influence of lattice misfit on the ductility effect of Hr. It is found that though Hf prefers to substitute A1 rather than Ni in Ni3A1 phase within most of the investigated misfit range, its stronger preferring to Ni phase than NiaA1 phase makes it impossible to go into Ni3A1 phase to occupy A1 site in Ni-Ni3A1 alloys. Bond order analysis in Hf-free case shows that lattice misfit has different effects on the Griffith work of interfacial cleavage 27int/E and the maximum theoretical shear stress Zmax of Ni and Ni3A1, contributing to the existence of anomalous strength-temperature phenomena in NiaA1 alloys. However, the addition of Hf will make the 27int/E （or Zmax） of both Ni3A1 and Ni decrease （or increase） with lattice misfit, indicating that the addition of Hf may make the anomalous strength-temperature relationship in Ni3A1 region disappear locally.
基金financially supported by the National Key Research and Development Program(No.2018YFA0702900)the National Natural Science Foundation of China(Nos.51774265 and 51701225)+3 种基金the National Science and Technology Major Project of China(Nos.2019ZX06004010 and 2017-VII008-0101)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDC04000000)the LingChuang Research Project of China National Nuclear Corporation Program of CAS Interdisciplinary Innovation TeamYouth Innovation Promotion Association,CAS。
文摘The interfacial oxidation behavior of Cr_(4)Mo_(4) V high-speed steel(HSS)joints undergoing hot-compression bonding was investigated by using optical microscopy(OM),scanning electron microscopy(SEM),and transmission electron microscopy(TEM).In the heating and holding processes,dispersed rod-like and granularδ-Al_(2)O_(3) oxides were formed at the interface and in the matrix near the interface due to the selective oxidation and internal oxidation of Al,while irregular Si-Al-O compounds and spheroidal SiO_(2) particles were formed at the interface.After the post-holding treatment,SiO_(2) oxides and Si-Al-O compounds were dissolved into the matrix,andδ-Al_(2)O_(3) oxides were transformed into nanoscaleα-Al_(2)O_(3) particles,which did not deteriorate the mechanical properties of the joints.The formation and migration of newly-formed grain boundaries by plastic deformation and post-holding treatment were the main mechanism for interface healing.The tensile test results showed that the strength of the healed joints was comparable to that of the base material,and the in-situ tensile observations proved that the fracture was initiated at the grain boundary of the matrix rather than at the interface.The clarification of interfacial oxides and microstructure is essential for the application of hot-compression bonding of HSSs.
基金financially supported by the National Key Research and Development Program of China(No.2021YFB3800504)the Tianshan Innovation Team Program of Xinjiang Uygur Autonomous Region(Grand No.2020D14038)+1 种基金the Department of Education of Guangdong in China(Nos.2021KCXTD050,2018KZDXM069)the National Natural Science Foundation of China(Grant No.51871056)。
文摘Nanoporous metals have attracted signifi cant attention owing to their excellent physical,chemical,and biological properties.However,preparing ultrafi ne nanoporous metal particles(1–5μm)with specifi c geometries remains challenging.Herein,we report a simple strategy to prepare ultrafi ne fl aky hexagonal nanoporous Au-Cu and Au particles via dealloying.Mg-based alloy ribbons with ultrafi ne fl aky hexagonal Mg-Au(Cu)-Gd particles dispersed in a Mg-Cu(Au)-Gd metallic glassy matrix were prepared.The size and morphology of the precipitated fl aky hexagonal Mg-Au(Cu)-Gd particles were controlled by the solidifi cation process of a Mg 61 Cu 21 Au 7 Gd 11 alloy melt.Ultrafi ne fl aky hexagonal nanoporous Au-Cu particles(diagonal diameter 2.58±0.44μm,ligament size~28 nm),Au-1 particles(diagonal diameter 2.38±0.35μm,ligament size~83 nm)and Au-2 particles(diagonal diameter 2.39±0.44μm,ligament size~66 nm)were prepared via ultrasonic-assisted dealloying of Mg 61 Cu 21 Au 7 Gd 11 alloy ribbons in 0.25 M HCl/ethanol,1 M HCl/ethanol and 0.25 M HNO 3/ethanol solutions,respectively.The ultrafi ne fl aky hexagonal nanoporous Au-Cu and Au particles with a large specifi c surface area have a uniform particle size and shape,implying that they possess adequate powder fl uidity and excellent catalytic properties.Moreover,the formation mechanism of the MgAu(Cu)Gd phase in solidifi ed Mg-Cu-Au-Gd alloys was discussed.This study provides a novel approach for synthesizing nanoporous metal particles with a specifi c geometry.
