The boron isotope paleo-pH proxy has been extensively studied due to its potential for understanding past climate change, and further calibrations were considered for accurate applications of the proxy because of sign...The boron isotope paleo-pH proxy has been extensively studied due to its potential for understanding past climate change, and further calibrations were considered for accurate applications of the proxy because of significant variability related to biocarbonate microstructure. In this work, we studied the boron isotopic fractionation between modern marine corals and their coexisting seawater collected along shallow area in Sanya Bay, South China Sea. The apparent partition coefficient of boron（KD） ranged from 0.83×10-3 to 1.69×10-3, which are in good agreement with previous studies. As the analyzed coral skeleton（~5 g） spanned the growth time period of 1–2 years, we discussed the boron isotopic fractionation between pristine corals and modern seawater using the annual mean seawater pH of 8.12 in this sea area. Without taking the vital effect into account,（11B/10B）coral values of all living corals spread over the curves of（11B/10B）borate vs.（11B/10B）sw with the α4-3 values ranging from 0.974 to 0.982. After calibrating the biological effect on the calcifying fluid pH, the field-based calcification on calcifying fluid pH（i.e., Δ（pHbiol-pHsw）） for coral species of Acropora, Pavona, Pocillopora, Faviidae, and others including Proites are 0.42, 0.33, 0.36, 0.19, respectively, and it is necessary to be validated by coral culturing experiment in the future. Correlations in B/Ca vs. Sr/Ca and B/Ca vs. pHbiol approve temperature and calcifying fluid pH influence on skeletal B/Ca. Fundamental understanding of the thermodynamic basis of the boron isotopes in marine carbonates and seawater will strengthen the confidence in the use of paleo-pH proxy as a powerful tool to monitor atmospheric CO2 variations in the past.展开更多
Ti-6.5 Al-2.5 Sn-9 Zr-0.5 Mo-0.25 Si-1 Nb-1 W-0.1 Er-x B(x=0,0.1,0.2,0.4,0.6 and 0.8 wt%)with different boron contents are fabricated for investigation.Influences of boron element and its amounts on phase constitution...Ti-6.5 Al-2.5 Sn-9 Zr-0.5 Mo-0.25 Si-1 Nb-1 W-0.1 Er-x B(x=0,0.1,0.2,0.4,0.6 and 0.8 wt%)with different boron contents are fabricated for investigation.Influences of boron element and its amounts on phase constitutions,microstructures,textures and compression mechanical properties are carefully studied.With the increasing boron additions,contents of TiB phase increase,and the maximum intensities of textures decrease.Microstructures are significantly and continuously refined after adding boron element and with the increasing boron additions,and turning point of refinement rates for different microstructural parameters is found at 0.2 wt%boron content.Strengths increase monotonously,while elongations increase firstly and decrease afterwards.The maximum value of elongation is acquired at boron content of 0.2 wt%.On the premise of ensuring plasticity,0.2 wt%boron content is the most appropriate amount for microstructural refinement and mechanical properties enhancement for current nearαtitanium alloys.Meanwhile,aspect ratios of TiB whiskers increase with the increasing boron contents.Lots of near equiaxedαgrains orαgrains with irregular morphologies are discovered around TiB phase.Distorted and twistedαgrain boundaries are also obviously detected in boron containing alloys.Moreover,premature fracture of alloys containing TiB whiskers is largely influenced by the fracture of these brittle reinforcements.展开更多
基金supported by the National Natural Science Foundation of China (Nos. 40973002, 41073002 and 41173049) the Fundamental Research Funds for the Central Universities (No. 020614330005)
文摘The boron isotope paleo-pH proxy has been extensively studied due to its potential for understanding past climate change, and further calibrations were considered for accurate applications of the proxy because of significant variability related to biocarbonate microstructure. In this work, we studied the boron isotopic fractionation between modern marine corals and their coexisting seawater collected along shallow area in Sanya Bay, South China Sea. The apparent partition coefficient of boron（KD） ranged from 0.83×10-3 to 1.69×10-3, which are in good agreement with previous studies. As the analyzed coral skeleton（~5 g） spanned the growth time period of 1–2 years, we discussed the boron isotopic fractionation between pristine corals and modern seawater using the annual mean seawater pH of 8.12 in this sea area. Without taking the vital effect into account,（11B/10B）coral values of all living corals spread over the curves of（11B/10B）borate vs.（11B/10B）sw with the α4-3 values ranging from 0.974 to 0.982. After calibrating the biological effect on the calcifying fluid pH, the field-based calcification on calcifying fluid pH（i.e., Δ（pHbiol-pHsw）） for coral species of Acropora, Pavona, Pocillopora, Faviidae, and others including Proites are 0.42, 0.33, 0.36, 0.19, respectively, and it is necessary to be validated by coral culturing experiment in the future. Correlations in B/Ca vs. Sr/Ca and B/Ca vs. pHbiol approve temperature and calcifying fluid pH influence on skeletal B/Ca. Fundamental understanding of the thermodynamic basis of the boron isotopes in marine carbonates and seawater will strengthen the confidence in the use of paleo-pH proxy as a powerful tool to monitor atmospheric CO2 variations in the past.
基金the Industrial Strengthen Foundation Project of Ministry of Industry and Information Technology,PRC(No.TC150B5C0-02)。
文摘Ti-6.5 Al-2.5 Sn-9 Zr-0.5 Mo-0.25 Si-1 Nb-1 W-0.1 Er-x B(x=0,0.1,0.2,0.4,0.6 and 0.8 wt%)with different boron contents are fabricated for investigation.Influences of boron element and its amounts on phase constitutions,microstructures,textures and compression mechanical properties are carefully studied.With the increasing boron additions,contents of TiB phase increase,and the maximum intensities of textures decrease.Microstructures are significantly and continuously refined after adding boron element and with the increasing boron additions,and turning point of refinement rates for different microstructural parameters is found at 0.2 wt%boron content.Strengths increase monotonously,while elongations increase firstly and decrease afterwards.The maximum value of elongation is acquired at boron content of 0.2 wt%.On the premise of ensuring plasticity,0.2 wt%boron content is the most appropriate amount for microstructural refinement and mechanical properties enhancement for current nearαtitanium alloys.Meanwhile,aspect ratios of TiB whiskers increase with the increasing boron contents.Lots of near equiaxedαgrains orαgrains with irregular morphologies are discovered around TiB phase.Distorted and twistedαgrain boundaries are also obviously detected in boron containing alloys.Moreover,premature fracture of alloys containing TiB whiskers is largely influenced by the fracture of these brittle reinforcements.
文摘利用金相组织观察、冲击试验和热膨胀试验,研究了B元素含量变化对高强钢药芯焊丝焊缝金属中针状铁素体形成的影响,得到了不同试验温度下焊缝金属冲击吸收功.结合透射电镜分析和分级淬火试验从热力学和动力学的角度对B元素影响机理进行了分析.结果表明,焊缝金属组织晶界中含有自由状态的B元素具有抑制晶界铁素体形核利于针状铁素体生成的作用;N元素含量增加会降低晶界B元素含量,并提高奥氏体向铁素体转变的温度,减少针状铁素体含量;针状铁素体是在以Ti元素和Mn元素的氧化物为核心,以Cu元素和Mn元素的硫化物为外层,以BN为过渡层的复杂结构上形核并长大的;针状铁素体含量的增加有利于提高焊缝金属冲击吸收功,–60℃冲击吸收功最大为70 J.
