Effect of silicon on oxidation behavior of GH3230 alloy

The high temperature oxidation behavior of GH3230 was investigated at 1100?? in air by means of TGA, XRD and SEM. The precipitation process of oxides is visually described. The results show that: the effect of Si element on high temperature oxidation of alloy is mainly reflected in two aspects. On the one hand, Si slows down the diffusion of Mn element in the oxidation process of alloy and causes difference in the composition of oxide scale after high temperature oxidation of GH3230 alloy; the main components of the oxide scale on the surface after oxidation at 1100?? of the alloy that exclude Si elements are MnCr2O4 and Cr2O3, and of the alloy that contain Si element are Cr2O3. On the other hand, SiO2 is formed in the early stage of the oxidation of the alloy, which plays an important role in the further oxidation of the alloy and contributes to suppress the volatilization of chromium oxide in the later stage of oxidation.     

GH761变形高温合金的热变形行为

镍基GH761合金热模拟压缩实验表明,当变形温度Td一定时,随应变速率ε的降低,变形峰值应力σp和稳态流动开始应力σs日及与它们对应的应变εp和εs均降低;当应变速率一定时,随Td的升高,σp和σs以及εs均降低,但εp基本不变.细化原始晶粒可提高再结晶形核率,在此基础上降低变形温度和提高变形速率是细化最终晶粒的重要途径.当应变达到完全再结晶时,合金具有最均匀且细小的组织;超过这一应变值,晶粒开始长大.GH761合金的热变形本构方程为:ε=6.5×106σp4.86exp(-461×103/RT).     

组织特征对GH864合金裂纹扩展行为的影响

通过组织分析试验、裂纹扩展速率试验和断口形貌分析手段,研究了GH864合金的微观组织及裂纹扩展行为,比较了不同组织状态下合金的裂纹扩展速率,并用Paris公式对裂纹扩展速率的结果进行了描述。结果表明:处理后合金的裂纹扩展速率都明显降低;粗晶组织能显著降低合金的裂纹扩展速率;晶界析出相对裂纹扩展速率有较大作用,而强化相大小尺寸γ′相对裂纹扩展速率影响不明显。     

Brain Recovery after a Plane Crash: Treatment with Growth Hormone (GH) and Neurorehabilitation: A Case Report

The aim of this study is to describe the results obtained after growth hormone (GH) treatment and neurorehabilitation in a young man that suffered a very grave traumatic brain injury (TBI) after a plane crash. Methods: Fifteen months after the accident, the patient was treated with GH, 1 mg/day, at three-month intervals, followed by one-month resting, together with daily neurorehabilitation. Blood analysis at admission showed that no pituitary deficits existed. At admission, the patient presented: spastic tetraplegia, dysarthria, dysphagia, very severe cognitive deficits and joint deformities. Computerized tomography scanners (CT-Scans) revealed the practical loss of the right brain hemisphere and important injuries in the left one. Clinical and blood analysis assessments were performed every three months for three years. Feet surgery was needed because of irreducible equinovarus. Results: Clinical and kinesitherapy assessments revealed a prompt improvement in cognitive functions, dysarthria and dysphagia disappeared and three years later the patient was able to live a practically normal life, walking alone and coming back to his studies. No adverse effects were observed during and after GH administration. Conclusions: These results, together with previous results from our group, indicate that GH treatment is safe and effective for helping neurorehabilitation in TBI patients, once the acute phase is resolved, regardless of whether or not they have GH-deficiency (GHD).     

航空GH2036合金硬度热处理优化及疲劳性能DIC分析

为探究热处理工艺参数对GH2036合金硬度及疲劳性能的影响,基于四因素三水平正交热处理实验,对GH2036铁基高温合金的硬度性能进行优化,并分析热处理后的显微组织;同时利用疲劳实验与DIC(digital image correlation)非接触全场应变测量相结合的方法,利用Y方向应变-疲劳寿命比的云图,直观地分析热处理后GH2036合金疲劳失效过程。结果表明:固溶温度对合金硬度性能的影响最大,其次是固溶时间、时效时间、时效温度,极差分析所得的最优热处理工艺为960℃/60 min+水冷+560℃/2 h;正交试验中最高显微维氏硬度(HV305.34)较未处理试样(HV260.41)提高17.3%;热处理后金相组织基体为奥氏体,增强相为第二相碳化物,显微硬度值随着奥氏体中的第二相碳化物含量的增加而升高;热处理后平均疲劳寿命(942372次循环)较未处理试样(450800次循环)提高109%,疲劳性能明显优化。     

固溶处理对GH3625合金板材组织及性能的影响

通过OM、SEM、EDS能谱分析和万能拉伸试验机以及洛氏硬度计等手段研究了固溶处理对GH3625合金板材组织和力学性能的影响。结果表明:固溶处理后合金的晶粒基本上呈等轴状态,且内部存在大量退火孪晶;当固溶温度高于1 130℃时,合金中的碳化物几乎完全溶解到基体中;在890~1 190℃固溶时,晶粒尺寸随温度的升高而增加,且晶粒长大激活能Qg为227.18kJ/mol;在不同的固溶温度下,晶粒尺寸与GH3625合金的室温力学性能符合Hall-Petch关系,合金的强化机制主要为细晶强化;随着温度的升高,GH3625合金板材的断裂方式由脆性断裂逐渐演变为明显的韧性断裂。     

Insertion of a Loop Structure into the “Loopless” GH19 Chitinase from Bryum coronatum

Chitinases belonging to the GH19 family have diverse loop structure arrangements. A GH19 chitinase from rye seeds (RSC-c) has a full set of (six) loop structures that form an extended binding cleft from -4 to +4 (“loopful”), while that from moss (BcChi-A) lacks several loops and forms a shortened binding cleft from -2 to +2 (“loopless”). We herein inserted a loop involved in sugar residue binding at subsites +3 and +4 of RSC-c (Loop-II) into BcChi-A (BcChi-A+L-II), and the thermal stability and enzymatic activity of BcChi-A+L-II were then characterized and compared with those of BcChi-A. The transition temperature of thermal unfolding decreased from 77.2 ˚C (BcChi-A) to 63.3 ˚C (BcChi-A+L-II) by insertion of Loop-II. Enzymatic activities toward the chitin tetramer (GlcNAc)₄ and the polymeric substrate glycol chitin were also suppressed by the Loop-II insertion to 12 and 9 %, respectively. The Loop-II inserted into BcChi-A was found to be markedly flexible and disadvantageous for protein stability and enzymatic activity.     

GH4169合金热加工过程中的显微组织演化数学模型

采用Thermecmastor—Z型热加工模拟试验机对GH4169合金热态变形过程中(温度范围为960～1020℃，应变速率范围为10^-2～50s^-1，等效应变范围为0．357～0．916和变形后高温滞留阶段内(滞留时间为0～15s)的显徽组织演化过程进行了实验研究，定量地测定了试样内的动态再结晶晶粒尺寸和再结晶体积分数。根据实验结果，指出了GH41．69合金热加工过程中的主要显微组织演化过程是动态和亚动态再结晶，确定了峰值应力和峰值应变与锻造热力参数间的关系，建立了动态再结晶和亚动态再结晶过程的运动学方程和晶粒尺寸演化模型，从而为预测和控制GH4169合金锻件的组织性能提供了依据。     

GH169合金涡轮盘680℃长期时效组织及其性能的变化规律

研究了ＧＨ１６９合金ＤＡ在６８０℃温度下长期时效时，盘件显微组织及其拉伸性能的变化规律，６８０℃时效超过５００ｈ后，钭引起盘件和性能的变化。