How to increase strength without sacrificing ductility has been developed as a key goal in the manufacture of high-performance metals or alloys. Herein, the double-nanophase intragranular yttrium oxide dispersion stre...How to increase strength without sacrificing ductility has been developed as a key goal in the manufacture of high-performance metals or alloys. Herein, the double-nanophase intragranular yttrium oxide dispersion strengthened iron alloy with high strength and appreciable ductility was fabricated by solution combustion route and subsequent spark plasma sintering, and the influences of yttrium oxide content and sintering temperature on microstructures and mechanical properties were investigated. The results show at the same sintering temperature,with the increase of yttrium oxide content, the relative density of the sintered alloy decreases and the strength increases. For Fe–2wt%Y_(2)O_(3)alloy, as the sintering temperature increases gradually, the compressive strength decreases, while the strain-to-failure increases. The Fe–2wt%Y_(2)O_(3)alloy with 15.5 nm Y_(2)O_(3)particles uniformly distributed into the 147.5 nm iron grain interior sintered at 650℃ presents a high ultimate compressive strength of 1.86 GPa and large strain-to-failure of 29%. The grain boundary strengthening and intragranular second-phase particle dispersion strengthening are the main dominant mechanisms to enhance the mechanical properties of the alloy.展开更多
In this study, the influences of La_(2)O_(3) added on the phase, morphology and reduction process of tungsten oxide prepared by solution combustion synthesis(SCS) were investigated for the first time. And tungsten nan...In this study, the influences of La_(2)O_(3) added on the phase, morphology and reduction process of tungsten oxide prepared by solution combustion synthesis(SCS) were investigated for the first time. And tungsten nanopowders with different La_(2)O_(3) doping amount(0.5~5.0 wt%) were successfully prepared by SCS and followed hydrogen reduction. The results showed that with the increase of La_(2)O_(3) addition,the product synthesized by SCS changed from needle-like W_(18) O_(49) to irregularly granulated H0.53 WO3 and the complete reduction temperature also increased form 700°C to 850°C. The densification behavior of as-prepared W nanopowders revealed that the densification inhibitory effect of La_(2)O_(3) was enhanced as the La_2O_3 addition increased. Nevertheless, due to the optimal size and distribution of La_(2)O_(3) particles,the sample with 2.0 wt% La_(2)O_(3) addition has a smallest grain size of 0.47 μm and a highest microhardness value of 739.3 Hv0.2, which are the best compared with the literature.展开更多
Based on Mansevich-Mawhin continuation theorem and some analysis skill, some new sufficient conditions for the existence of periodic solutions to a duffing type p-Laplacian differential equation with several p-Laplaci...Based on Mansevich-Mawhin continuation theorem and some analysis skill, some new sufficient conditions for the existence of periodic solutions to a duffing type p-Laplacian differential equation with several p-Laplacian operators are obtained. Moreover, we construct an example to illustrate the feasibility of our results.展开更多
基金financially supported by the Guangdong Basic and Applied Basic Research Foundation,China (No.2021A1515110202)the Natural Science Foundation Program of Beijing,China (Nos.2224104,2202031,2174079+6 种基金2162027)the National Natural Science Foundation Program of China (Nos.52131307,52130407,52071013,52104359,51774035,and 52174344)the Scientific and Technological Innovation Foundation of Foshan,China (No.BK21BE007)the National Key Research and Development Program of China (Nos.2021YFB3701900,2022YFB3705400,and 2022YFB3708800)the Beijing Municipal Science & Technology Commission,Administrative Commission of Zhongguancun Science Park,China (No.Z221100005822001)the S&T Program of Hebei,China(No.20311001D)the Fundamental Research Funds for the Central Universities (Nos.FRF-IDRY-20-022,FRF-TP-20-032A2,FRF-TP-20-100A1Z,and FRF-IDRY-22-030)。
文摘How to increase strength without sacrificing ductility has been developed as a key goal in the manufacture of high-performance metals or alloys. Herein, the double-nanophase intragranular yttrium oxide dispersion strengthened iron alloy with high strength and appreciable ductility was fabricated by solution combustion route and subsequent spark plasma sintering, and the influences of yttrium oxide content and sintering temperature on microstructures and mechanical properties were investigated. The results show at the same sintering temperature,with the increase of yttrium oxide content, the relative density of the sintered alloy decreases and the strength increases. For Fe–2wt%Y_(2)O_(3)alloy, as the sintering temperature increases gradually, the compressive strength decreases, while the strain-to-failure increases. The Fe–2wt%Y_(2)O_(3)alloy with 15.5 nm Y_(2)O_(3)particles uniformly distributed into the 147.5 nm iron grain interior sintered at 650℃ presents a high ultimate compressive strength of 1.86 GPa and large strain-to-failure of 29%. The grain boundary strengthening and intragranular second-phase particle dispersion strengthening are the main dominant mechanisms to enhance the mechanical properties of the alloy.
基金financially supported by the National Key R&D Program of China (2017YFB0306000 and 2017YFB0305600)the National Natural Science Foundation Program of China (51574031,51604239,51604240 and 51674095)+2 种基金the Natural Science Foundation Program of Beijing (2162027)the General Project of the Education Department of Hunan Province (15C1308)the Fundamental Research Funds for the Central Universities(JZ2017HGBZ0920)。
文摘In this study, the influences of La_(2)O_(3) added on the phase, morphology and reduction process of tungsten oxide prepared by solution combustion synthesis(SCS) were investigated for the first time. And tungsten nanopowders with different La_(2)O_(3) doping amount(0.5~5.0 wt%) were successfully prepared by SCS and followed hydrogen reduction. The results showed that with the increase of La_(2)O_(3) addition,the product synthesized by SCS changed from needle-like W_(18) O_(49) to irregularly granulated H0.53 WO3 and the complete reduction temperature also increased form 700°C to 850°C. The densification behavior of as-prepared W nanopowders revealed that the densification inhibitory effect of La_(2)O_(3) was enhanced as the La_2O_3 addition increased. Nevertheless, due to the optimal size and distribution of La_(2)O_(3) particles,the sample with 2.0 wt% La_(2)O_(3) addition has a smallest grain size of 0.47 μm and a highest microhardness value of 739.3 Hv0.2, which are the best compared with the literature.
基金sponsored by the National Natural Science Foundation of China (11071001)NSF of Education Bureau of Anhui Province (KJ2009A005Z+2 种基金KJ2010ZD022010SQRL159)Anhui Provincial Natural Science Foundation (1208085MA13)
文摘Based on Mansevich-Mawhin continuation theorem and some analysis skill, some new sufficient conditions for the existence of periodic solutions to a duffing type p-Laplacian differential equation with several p-Laplacian operators are obtained. Moreover, we construct an example to illustrate the feasibility of our results.
