The microstructure and the stability of carbides after heat treatments in an H23 tool steel were investigated. The heat treatments consisted of austenization at two different austenizing temperatures （1100℃ and 125...The microstructure and the stability of carbides after heat treatments in an H23 tool steel were investigated. The heat treatments consisted of austenization at two different austenizing temperatures （1100℃ and 1250℃）, followed by water quenching and double-aging at 650℃, 750℃, and 800℃with air cooling between the first and second aging treatments. Martensite did not form in the as-quenched micro- structures, which consisted of a ferrite matrix, M6C, M7C3, and MC carbides. The double-aged microstructures consisted of a ferrite matrix and MC, M6C, M7C3, and M23C6 carbides. Secondary hardening as a consequence of secondary precipitation of fine M2C carbides did not occur. There was disagreement between the experimental microstructure and the results of thermodynamic calculations. The highest double-aged hardness of the H23 tool steel was 448 HV after austenization at 1250℃ and double-aging at 650℃, which suggested that this tool steel should be used at temperatures below 650℃.展开更多
The effects of in-situ generated coinage nanometals（Cu,Ag and Au） on crystallization behavior,microstructure,thermal and mechanical properties of SiO2-MgO-Al2O3-B2O3-K2O-MgF2（BMAPS） glassceramics were systematical...The effects of in-situ generated coinage nanometals（Cu,Ag and Au） on crystallization behavior,microstructure,thermal and mechanical properties of SiO2-MgO-Al2O3-B2O3-K2O-MgF2（BMAPS） glassceramics were systematically studied.On addition of coinage nanometai,the glass transition temperature（Tg） is increased by 20-30 ℃,crystallization temperature（Tc） by 30-50 ℃ and dilatometric softening temperature（Td） by 10-25 ℃.It was found that the density of Cu-containing glass was 2.59 g cm-3and for other glasses it was in the range of 2.56-2.57 g cm-3.From the non-isothermal differential scanning calorimetry study,the activation energy of crystallization for BMAPS base glass was calculated as 344 kJ/mol,and changed to 406,334 and 274 kJ/mol on addition of Cu,Ag and Au-nanometals,respectively.Crystals evolved in the opaque BMAPS glass-ceramics derived by controlled heat treatment,were identified as fluorophlogopite mica(KMg3(AlSi3O10)F2) by X-ray diffraction（XRD） technique and confirmed by Fourier transformed infrared spectroscopy.Presences of copper,silver and gold nanometals were also identified by XRD technique.It is found from field emission scanning electron microscopy that the interlocked grain like microstructure developed in BMAPS glass-ceramics（being heat-treated at 1050 ℃ for 4 h） changed to denser house-of-cards like microstructure（containing smaller sized mica crystals） on addition of coinage nanometals.Density of BMAPS base glass-ceramic was 2.60 g cm-3and marginally changed to 2.61-2.62 g cm-3on addition of Cu,Ag and Au-nanometals.The change in microstructure resulted in the decrease of Vickers micro hardness value from 5.37 to 4.12,4.20 and 4.58 GPa on addition of Cu,Ag and Au,respectively.Coinage nanometai doped mica glass-ceramics containing interlocked microstructure with higher thermal expansion coefficient,hence,is suitable for high temperature sealing application（like solid oxide fuel cell）.展开更多
The titanium nitride (TiNx) thin film with a controllable surface structure was fabricated by the dc-reactive magnetron sputtering technique, and the variation of microstructure in the surface layer with the energy of...The titanium nitride (TiNx) thin film with a controllable surface structure was fabricated by the dc-reactive magnetron sputtering technique, and the variation of microstructure in the surface layer with the energy of condensed adatom was investigated through X-ray diffraction (XRD) pattern and transmission electron microscope(TEM). It was found that the lattice parameters and the full width at half maximum (fwhm) of XRD peak on the top layers in the preferred orientation of (111) and (002) were closely correlated to the impacting induced phase composition, compressive strain, crystallite size and the fault density of the thin films. In the theory, a new means was used to model the atomistic process of per condensed adatom. The average energy at least in the minimum energy state of the incorporate adatom on TiN surface layer was statistically formulized through a careful consideration of dynamical process, which properly interpreted the experimental observations.展开更多
基金the Directorate of Higher Education, Indonesian Government and to the Institut Teknologi Nasional (Itenas), Bandung, Indonesia for their financial support
文摘The microstructure and the stability of carbides after heat treatments in an H23 tool steel were investigated. The heat treatments consisted of austenization at two different austenizing temperatures （1100℃ and 1250℃）, followed by water quenching and double-aging at 650℃, 750℃, and 800℃with air cooling between the first and second aging treatments. Martensite did not form in the as-quenched micro- structures, which consisted of a ferrite matrix, M6C, M7C3, and MC carbides. The double-aged microstructures consisted of a ferrite matrix and MC, M6C, M7C3, and M23C6 carbides. Secondary hardening as a consequence of secondary precipitation of fine M2C carbides did not occur. There was disagreement between the experimental microstructure and the results of thermodynamic calculations. The highest double-aged hardness of the H23 tool steel was 448 HV after austenization at 1250℃ and double-aging at 650℃, which suggested that this tool steel should be used at temperatures below 650℃.
基金Dr.R.N.Basu,Fuel Cell and Battery Division of CSIR-CGCRI for financial support through NMITLI-CSIR sponsored project on solid oxide fuel cell(TLP 0005)
文摘The effects of in-situ generated coinage nanometals（Cu,Ag and Au） on crystallization behavior,microstructure,thermal and mechanical properties of SiO2-MgO-Al2O3-B2O3-K2O-MgF2（BMAPS） glassceramics were systematically studied.On addition of coinage nanometai,the glass transition temperature（Tg） is increased by 20-30 ℃,crystallization temperature（Tc） by 30-50 ℃ and dilatometric softening temperature（Td） by 10-25 ℃.It was found that the density of Cu-containing glass was 2.59 g cm-3and for other glasses it was in the range of 2.56-2.57 g cm-3.From the non-isothermal differential scanning calorimetry study,the activation energy of crystallization for BMAPS base glass was calculated as 344 kJ/mol,and changed to 406,334 and 274 kJ/mol on addition of Cu,Ag and Au-nanometals,respectively.Crystals evolved in the opaque BMAPS glass-ceramics derived by controlled heat treatment,were identified as fluorophlogopite mica(KMg3(AlSi3O10)F2) by X-ray diffraction（XRD） technique and confirmed by Fourier transformed infrared spectroscopy.Presences of copper,silver and gold nanometals were also identified by XRD technique.It is found from field emission scanning electron microscopy that the interlocked grain like microstructure developed in BMAPS glass-ceramics（being heat-treated at 1050 ℃ for 4 h） changed to denser house-of-cards like microstructure（containing smaller sized mica crystals） on addition of coinage nanometals.Density of BMAPS base glass-ceramic was 2.60 g cm-3and marginally changed to 2.61-2.62 g cm-3on addition of Cu,Ag and Au-nanometals.The change in microstructure resulted in the decrease of Vickers micro hardness value from 5.37 to 4.12,4.20 and 4.58 GPa on addition of Cu,Ag and Au,respectively.Coinage nanometai doped mica glass-ceramics containing interlocked microstructure with higher thermal expansion coefficient,hence,is suitable for high temperature sealing application（like solid oxide fuel cell）.
文摘The titanium nitride (TiNx) thin film with a controllable surface structure was fabricated by the dc-reactive magnetron sputtering technique, and the variation of microstructure in the surface layer with the energy of condensed adatom was investigated through X-ray diffraction (XRD) pattern and transmission electron microscope(TEM). It was found that the lattice parameters and the full width at half maximum (fwhm) of XRD peak on the top layers in the preferred orientation of (111) and (002) were closely correlated to the impacting induced phase composition, compressive strain, crystallite size and the fault density of the thin films. In the theory, a new means was used to model the atomistic process of per condensed adatom. The average energy at least in the minimum energy state of the incorporate adatom on TiN surface layer was statistically formulized through a careful consideration of dynamical process, which properly interpreted the experimental observations.
