As the raw materials in the post process of rolling and heat treatment, ingots have great effects on the properties of the final products. Inclusions and solidification structures are the most important aspects of the...As the raw materials in the post process of rolling and heat treatment, ingots have great effects on the properties of the final products. Inclusions and solidification structures are the most important aspects of the quality of ingots. Niobium and titanium are usually used to react with carbon and nitrogen to improve the properties of ferritic stainless steels. In this research, combined with thermodynamic calculation, effects of niobium and titanium on the inclusions and solidification structures in three kinds of high pure ferritic stainless steels with different titanium additions were investigated by optical microscope（OM）, scanning electron microscope（SEM）, transmission electron microscope（TEM）, and energy disperse spectrometer（EDS）. Results show that Al2O3 and a few（Nb,Ti）N particles form when titanium addition is 0.01 %.Furthermore, inclusions are mainly Ti N and Al2O3–Ti Ox–Ti N duplex inclusions when titanium addition is more than0.10 %. Those two types of inclusions are in well distribution, and can afford nuclei to the solidification process.Therefore, the ratio of equiaxed zone increases with the increase of titanium addition. The ratio increases from42.1 % to 64.0 % with the titanium addition increasing from 0.01 % to 0.10 %, and it increases to 85.7 % when the titanium addition reaches 0.34 %.展开更多
为探究湖北襄阳地区高温大曲中芽孢杆菌(Bacillus)菌群多样性,该研究通过下载并筛选高温大曲样品芽孢杆菌相对含量>2.0%的测序数据,采用Illumina Mi Seq高通量测序技术和传统纯培养技术相结合的方法对大曲样品中芽孢杆菌多样性进行...为探究湖北襄阳地区高温大曲中芽孢杆菌(Bacillus)菌群多样性,该研究通过下载并筛选高温大曲样品芽孢杆菌相对含量>2.0%的测序数据,采用Illumina Mi Seq高通量测序技术和传统纯培养技术相结合的方法对大曲样品中芽孢杆菌多样性进行解析。结果表明,高温大曲中芽孢杆菌相对含量>2.0%的样品共有12份,包括8份白色大曲样品和4份黄色大曲样品,所有样品共获得77 825条代表性序列,1 197个操作分类单元(OTUs)。多样性分析结果表明,较之黄色大曲,白色大曲样品中芽孢杆菌的超1指数和发现物种数显著偏高(P<0.05)。OTU分析结果表明,OTU5321和OTU5291在所有样品中均存在,其在白色大曲和黄色大曲中累积包含序列分别占总序列数的49.43%和41.32%。传统纯培养技术分析结果表明,解淀粉芽孢杆菌(Bacillus amyloliquefaciens)为高温大曲中芽孢杆菌的主要可培养菌种。由此可知,白色大曲芽孢杆菌群落结构的丰富度更高,且解淀粉芽孢杆菌为高温大曲中芽孢杆菌的主要可培养菌种,为后续高温大曲中芽孢杆菌的应用及菌种选育具有指导作用。展开更多
为探究湖北襄阳地区不同颜色高温大曲中葡萄球菌(Staphylococcus)多样性,该研究通过下载并筛选葡萄球菌属相对含量>10%的样品序列,采用Illumina Mi Seq高通量测序技术和传统纯培养技术相结合的方法对大曲中葡萄球菌多样性进行解析。...为探究湖北襄阳地区不同颜色高温大曲中葡萄球菌(Staphylococcus)多样性,该研究通过下载并筛选葡萄球菌属相对含量>10%的样品序列,采用Illumina Mi Seq高通量测序技术和传统纯培养技术相结合的方法对大曲中葡萄球菌多样性进行解析。结果表明,高温大曲中葡萄球菌相对含量>10%的样品共有13份,包括7份黑色大曲、4份黄色大曲和2份白色大曲,葡萄球菌基因序列相对丰度占所有原核生物的14.33%~74.19%。多样性分析表明,黑色大曲中葡萄球菌丰富度和多样性均显著偏高(P<0.05),且不同颜色高温大曲中葡萄球菌群落结构差异显著(P<0.05)。操作分类单元(OTU)分析表明,高温大曲中共有OTU 5个,累积平均相对含量达到91.38%。传统纯培养技术表明,腐生葡萄球菌(Staphylococcus saprophyticus)是黑色、黄色和白色大曲中共有的可培养菌种,亦是高温大曲中葡萄球菌的主要可培养菌种。由此表明,黑色大曲中葡萄球菌丰富度和多样性更高,且腐生葡萄球菌为高温大曲中葡萄球菌的主要可培养菌种。展开更多
For further knowledge about the refining performance of AlTiC master alloys, Al5.5Ti0.25C and Al6.5Ti0.5C master alloys containing high Ti and C content were prepared and used in grain refining experiments of 99.8% co...For further knowledge about the refining performance of AlTiC master alloys, Al5.5Ti0.25C and Al6.5Ti0.5C master alloys containing high Ti and C content were prepared and used in grain refining experiments of 99.8% commercial pure aluminum(CPAl). Their performance was compared with two types of Al5Ti1B refiners whose performance was nowadays considered to be the best. These two types of master alloys show similar refining efficiency at the addition level of 0.2%. However, at the addition level of 0.5%, there still exists great performance difference between AlTiC and Al5TiB alloys in grain refinement of 99.98% and 99.995% high purity aluminum(HPAl). The growth of columnar grains is fully suppressed due to the refinement of AlTiC at the addition level of 0.5%. Also, at the same addition level, the grain refining experiments of Al3Ti0.15C and Al5Ti0.2C master alloys which have found initial commercial applications are conducted in the above-mentioned three types of pure aluminum. According to the experimental results, these two refiners of different compositions are both nonideal. The second phase particles extracted from each refiner were observed through TEM, while the nuclei of grains after grain refinement were observed through SEM. The results were analyzed through computation and comparison of the constitutional-supercooling parameter and the growth-restriction parameter whose values were determined by solute element in aluminum melt with different purity. Apparently, AlTiC master alloys with high content of Ti and C element have great refining potential.展开更多
基金financially supported by the Fundamental Research Funds for the Central Universities (No. N100602011)the National Natural Science Foundation of China (No. 51104039)+4 种基金the National Key Basic Research Program of China (No. 2012CB626812)the Program for New Century Excellent Talents in University (No. NCET-11-0077)Liaoning Provincial Natural Science Foundation of China (No. 201102062)Liaoning Provincial Science and Technology Plan (No. 2012221013)the National Innovation Experiment Program for University Students
文摘As the raw materials in the post process of rolling and heat treatment, ingots have great effects on the properties of the final products. Inclusions and solidification structures are the most important aspects of the quality of ingots. Niobium and titanium are usually used to react with carbon and nitrogen to improve the properties of ferritic stainless steels. In this research, combined with thermodynamic calculation, effects of niobium and titanium on the inclusions and solidification structures in three kinds of high pure ferritic stainless steels with different titanium additions were investigated by optical microscope（OM）, scanning electron microscope（SEM）, transmission electron microscope（TEM）, and energy disperse spectrometer（EDS）. Results show that Al2O3 and a few（Nb,Ti）N particles form when titanium addition is 0.01 %.Furthermore, inclusions are mainly Ti N and Al2O3–Ti Ox–Ti N duplex inclusions when titanium addition is more than0.10 %. Those two types of inclusions are in well distribution, and can afford nuclei to the solidification process.Therefore, the ratio of equiaxed zone increases with the increase of titanium addition. The ratio increases from42.1 % to 64.0 % with the titanium addition increasing from 0.01 % to 0.10 %, and it increases to 85.7 % when the titanium addition reaches 0.34 %.
文摘为探究湖北襄阳地区不同颜色高温大曲中葡萄球菌(Staphylococcus)多样性,该研究通过下载并筛选葡萄球菌属相对含量>10%的样品序列,采用Illumina Mi Seq高通量测序技术和传统纯培养技术相结合的方法对大曲中葡萄球菌多样性进行解析。结果表明,高温大曲中葡萄球菌相对含量>10%的样品共有13份,包括7份黑色大曲、4份黄色大曲和2份白色大曲,葡萄球菌基因序列相对丰度占所有原核生物的14.33%~74.19%。多样性分析表明,黑色大曲中葡萄球菌丰富度和多样性均显著偏高(P<0.05),且不同颜色高温大曲中葡萄球菌群落结构差异显著(P<0.05)。操作分类单元(OTU)分析表明,高温大曲中共有OTU 5个,累积平均相对含量达到91.38%。传统纯培养技术表明,腐生葡萄球菌(Staphylococcus saprophyticus)是黑色、黄色和白色大曲中共有的可培养菌种,亦是高温大曲中葡萄球菌的主要可培养菌种。由此表明,黑色大曲中葡萄球菌丰富度和多样性更高,且腐生葡萄球菌为高温大曲中葡萄球菌的主要可培养菌种。
基金Project (51074033) supported by the National Natural Science Foundation of China
文摘For further knowledge about the refining performance of AlTiC master alloys, Al5.5Ti0.25C and Al6.5Ti0.5C master alloys containing high Ti and C content were prepared and used in grain refining experiments of 99.8% commercial pure aluminum(CPAl). Their performance was compared with two types of Al5Ti1B refiners whose performance was nowadays considered to be the best. These two types of master alloys show similar refining efficiency at the addition level of 0.2%. However, at the addition level of 0.5%, there still exists great performance difference between AlTiC and Al5TiB alloys in grain refinement of 99.98% and 99.995% high purity aluminum(HPAl). The growth of columnar grains is fully suppressed due to the refinement of AlTiC at the addition level of 0.5%. Also, at the same addition level, the grain refining experiments of Al3Ti0.15C and Al5Ti0.2C master alloys which have found initial commercial applications are conducted in the above-mentioned three types of pure aluminum. According to the experimental results, these two refiners of different compositions are both nonideal. The second phase particles extracted from each refiner were observed through TEM, while the nuclei of grains after grain refinement were observed through SEM. The results were analyzed through computation and comparison of the constitutional-supercooling parameter and the growth-restriction parameter whose values were determined by solute element in aluminum melt with different purity. Apparently, AlTiC master alloys with high content of Ti and C element have great refining potential.
