Methods and mechanisms for uniformly refining deformed mixed and coarse grains inside a solution-treated Ni-based superalloy by two-stage heat treatment

The uniform refinement mechanisms and methods of deformed mixed and coarse grains inside a solution-treatment Ni-based superalloy during two-stage annealing treatment have been investigated.The two-stage heat treatment experiments include an aging annealing treatment(AT)and a subsequent recrystallization annealing treatment(RT).The object of AT is to precipitate some δ phases and consume part of storage energy to inhibit the grain growth during RT,while the RT is to refine mixed and coarse grains by recrystallization.It can be found that the recrystallization grains will quickly grow up to a large size when the AT time is too low or the RT temperature is too high,while the deformed coarse grains cannot be eliminated when the AT time is too long or the RT temperature is too low.In addition,the mixed microstructure composed of some abnormal coarse recrystallization grains(ACRGs)and a large number of fine grains can be observed in the annealed specimen when the AT time is 3 h and RT tem-perature is 980℃.The phenomenon attributes to the uneven distribution of δ phase resulted from the heterogeneous deformation energy when the AT time is too short.In the regions with a large number of δ phases,the recrystallization nucleation rate is promoted and the growth of grains is limited,which results in fine grains.However,in the regions with few δ phases,the recrystallization grains around grain boundaries can easily grow up,and the new recrystallization nucleus is difficult to form inside grain,which leads to ACRGs.Thus,in order to obtain uniform and fine annealed microstructure,it is a prereq-uisite to precipitate even-distributed δ phase by choosing a suitable AT time,such as 12 h.Moreover,a relative high RT temperature is also needed to promote the recrystallization nucleation around δ phase.The optimal annealing parameters range for uniformly refining mixed crystal can be summarized as:900℃×12 h+990℃×(40-60 min)and 900℃×12 h+1000℃×(10-15 min).     

空间的力量 新奥胡斯大学医院

正新奥胡斯大学医院是丹麦第一个超大型的医院案例,也是一个具有"康复医疗"概念的、超现代的国际先锋作品。医院的建筑设计通过系统运用"信息和循证"的工作方法,践行了"康复建筑"的综合理念。其"信息和循证"的方法是利用对现存建筑的研究和评估,以提供最有效的信息来创建最佳的康复建筑。从单人病房的设计、日光和光线的利用,以及景观和花园空间的设计,旨在尽量满足病人的需求,提升     

A boronic acid-based fluorescent hydrogel for monosaccharide detection

A boronic acid-based anthracene fluorescent probe was functionalised with an acrylamide unit to incorporate into a hydrogel system for monosaccharide detection. In solution, the fluorescent probe displayed a strong fluorescence turn-on response upon exposure to fructose, and an expected trend in apparent binding constants, as judged by a fluorescence response where D-fructose>D-galactose>D-mannose>D-glucose. The hydrogel incorporating the boronic acid monomer demonstrated the ability to detect monosaccharides by fluorescence with the same overall trend as the monomer in solution with the addition of D-fructose resulting in a 10-fold enhancement (≤0.25 mol/L).     

ZrCuAlNi系大块金属玻璃的非晶形成能力、热学和力学性能（英文）

分析ZrCuAlNi系大块金属玻璃的非晶形成能力、热学和力学性能。运用密实堆积和动态脆性指数模型从理论上确定合金的成分。采用铜模吸铸法在氩气保护下制备圆柱形和圆锥形铸锭。用X射线衍射表征圆锥形铸锭以便确定非晶结构。结果表明:两种合金的临界非晶直径为3 mm。用差示扫描量热法(DSC)分析其热行为,加热速率分别为0.5、0.67和0.83 K/s。γ参数、过冷液相区ΔT_x和约化玻璃转变温度T_(rg)等这些实验所得的参数均表明其具有高的非晶形成能力。非晶成分显示其脆性指数为40。合金的压缩试验采用的应变速率为0.016 s~(-1),得到弹性模量约为83 GPa,总应变约为5%,屈服强度为1.6 GPa,硬度为4 GPa。运用密实堆积和动态脆性指数模拟可以预测ZrCuAlNi系合金的非晶形成成分。     

硫醇-烯点击化学反应制备主链液晶弹性体

以自制的含三个苯环液晶基元的二烯单体与1,6-己二硫醇(DMH)在254 nm紫外光辐照下,以2-羟基-2-甲基苯基丙烷-1-酮(HDMPh)为光引发剂,以季戊四醇四-3-巯基丙酸酯(PETMP)为交联剂,通过硫醇-烯点击化学反应,制备了主链液晶聚合物与液晶弹性体。差示扫描量热法(DSC)、偏光显微镜(PLM)、广角X衍射(WAXD)测试结果表明,该主链聚合物与弹性体具有一个液晶转变点和向列型液晶纹影织构。当反应体系中添加光引发剂时,主链型液晶及其弹性体分子量较高,成膜性好,力学性能好;而未添加光引发剂的反应体系,得到的聚合物分子量较低,成膜性差,力学性能差。     

尊重斯德哥尔摩的历史中心—骑士岛的激活改造

正瑞典国家财产委员会拥有骑士岛的所有权与管理权,并计划对该岛上所有的公共空间进行更新和开发,以提高其可达性与吸引力。总的来说,从文化历史角度来看骑士岛很有     

Grain refinement in low SFE and particle-containing nickel aluminium bronze during severe plastic deformation at elevated temperatures

The influence of particle size and morphology on grain refinement in low stacking fault energy(SFE)alloys was studied by comparing the grain structures in single-and multi-phase Al-bronze(AB)alloys following equal channel angular pressing(ECAP)between 350 and 500℃.In particular,nickel aluminium bronze(NAB)was chosen as it contained both coarse and fine rounded particles,as well as a lamellar phase which evolved during ECAP.Grain refinement in the single-phase alloy was achieved through dynamic recrystallisation initiated at deformed twin boundaries.By contrast,different mechanisms were observed in the particle-containing NAB.Recrystallisation around the coarse κⅡ particles(～5 μm)was promoted through particle stimulated nucleation(PSN),whereas recrystallisation in the region of the fine κⅣ(～0.4μm)was delayed due to the activation of secondary slip.Grain refinement in areas of the lamellar κⅢ showed significant variation,depending on the lamellar orientation relative to the shear plane of ECAP.As the lamellae deformed,numerous high angle grain boundaries were generated between fragments and served as nucleation sites for recrystallisation,while PSN occurred around spheroidised lamellae.The spreading of the κⅢ particles by ECAP then enhanced the total area of recrystallised grains.     

Rare earth metals sorption recovery from uranium in situ leaching process solutions

Sorption characteristics of ion exchange resins 001×7,005×8,D72 regarding rare earth metals(REM) during extraction from barren solution of uranium sorption in dynamic conditions were investigated. It was identified that D72 resin capacity on analyzed REM was 2.46 mg cm-3 after passing 220 BV(bed volume) of initial solution with 95% recovery of element of REM with the lowest affinity. Researches on REM desorption in dynamic conditions from investigated ion exchange resins by solution of 1.7 mol·L-1HNO3 and 8.0 mol·L-1NH4NO3 with 0.2 mol·L-1 HNO3 passing were carried out. It was identified that using desorption solution based on ammonium nitrate allows to achieve acceptable recovery degree of REM from the resin. The possibility of organization of a circulating desorption solution system increases the perspectives of nitrate ammonium solution usage.