铸态Ti-25V-15Cr-0.3Si钛合金静态再结晶过程中的二次相析出位置及显微组织演变（英文）

利用热压缩和热处理实验研究铸态Ti-25V-15Cr-0.3Si钛合金的显微组织演变和二次相析出位置。研究在不同热处理温度和时间下晶粒的平均长宽比、平均面积和尺寸,分析变形量和退火参数对晶粒面积和尺寸的影响。结果表明,晶粒尺寸受变形量和退火时间影响显著,在950°C、变形量为30%、当退火时间从10 min增加至2 h时,晶粒明显长大;而当退火时间为2~4 h时,晶粒长大缓慢。此外,还观察到大量弥散质点以连续的链状存在,显微组织观察和TEM衍射花样分析证实沿着原始晶界析出的弥散质点为Ti_5Si_3相。

热加工过程中两相钛合金的α相与β相的协调演变

为了研究两相钛合金中α和β相的协调演变行为,在不同条件下对合金进行热压缩和热处理。研究结果表明,α和β相之间的协调变形能力能影响显微组织演变的均匀性。当变形协调能力较好时,α相保持原来的片状结构,β相的再结晶程度较低。此时,尽管变形较大,但α相与两侧的β相仍保持Burgers取向关系,α和β相之间的原始相界面没有被破坏。随着变形协调能力的下降,片状α相的变形程度及β相的再结晶程度增加。此时,α相仅与一侧的β相保持Burgers取向关系,而与另一侧的β相取向产生偏移,偏移角度在10°以内。当变形协调能力较差时,α相和β相发生较为严重的偏移,界面位错程度增大,α相与周围的β相偏离Burgers取向关系。

Development of a database system for operational use in the selection of titanium alloys

The selection of titanium alloys has become a complex decision-making task due to the growing number of creation and utilization for titanium alloys,with each having its own characteristics,advantages,and limitations.In choosing the most appropriate titanium alloys,it is very essential to offer a reasonable and intelligent service for technical engineers.One possible solution of this problem is to develop a database system（DS） to help retrieve rational proposals from different databases and information sources and analyze them to provide useful and explicit information.For this purpose,a design strategy of the fuzzy set theory is proposed,and a distributed database system is developed.Through ranking of the candidate titanium alloys,the most suitable material is determined.It is found that the selection results are in good agreement with the practical situation.

Attenuating effect of daidzein on polychlorinated biphenyls-induced oxidative toxicity in mouse testicular cells

The attenuating effect of daidzein (DAI) on oxidative toxicity induced by Aroclor 1254 (A1254) was investigated in mouse testicular cells. Cells were exposed to A1254 alone or with DAI. The oxidative damage was estimated by measuring malondialdehyde (MDA) formation, superoxide dismutase (SOD) activity and glutathione (GSH) content. Results show that A1254 induced a decrease of germ cell number, an elevation in thiobarbituric acid reactive substances (TBARS) but a decrease in SOD activity and GSH content. However, simultaneous supplementation with DAI decreased TBARS level and increased SOD activity and GSH content. Consequently, dietary DAI may restore the intracellular antioxidant system to attenuate the oxidative toxicity of A1254 in testicular cells.

不同产蛋阶段蛋鸡卵黄前体物质生成的变化研究（英文）

目的:比较不同日龄蛋鸡血清雌激素的水平、肝脏雌激素受体基因和卵黄前体物生成相关基因表达量、"肝脏-血液-卵巢轴"中甘油三酯和胆固醇的含量和肝脏抗氧化能力的动态变化,揭示蛋鸡卵黄前体物生成随着年龄增长的变化规律。创新点:首次发现在蛋鸡衰老过程中雌激素作用衰退以及肝脏抗氧化能力降低致使肝脏中卵黄前体物合成下降,最终导致蛋鸡的产蛋性能下降。方法:取90、150、280和580日龄蛋鸡各10只,检测血清中雌激素水平、肝脏雌激素受体基因表达水平、肝脏中卵黄前体物质合成和脂质代谢相关基因表达水平、"肝脏-血液-卵巢轴"中甘油三酯和胆固醇的含量及肝脏抗氧化能力,揭示蛋鸡卵黄前体物生成在衰老过程中的变化规律。结论:在蛋鸡衰老过程中,血清雌激素水平、肝脏雌激素受体基因和卵黄前体物质合成相关基因表达量降低,肝脏抗氧化能力降低,引起肝脏合成甘油三酯的能力下降,最终导致卵黄前体物质合成能力降低。

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 someδphases 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 temperature is 980℃.The phenomenon attributes to the uneven distribution ofδphase resulted from the heterogeneous deformation energy when the AT time is too short.In the regions with a large number ofδphases,the recrystallization nucleation rate is promoted and the growth of grains is limited,which results in fine grains.However,in the regions with fewδphases,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 prerequisite to precipitate even-distributedδphase by choosing a suitable AT time,such as 12 h.Moreover,a relative high RT temperature is also needed to promote the recrystallization nucleation aroundδphase.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).

Phase transformation kinetics of Ti-1300 alloy during continuous heating

Abstract The α ＋ β→β phase transformation kinetics of Ti-1300 alloy during continuous heating at different heating rates were investigated using dilatometric method. Results show that the curves of the α ＋ β→β phase transformation exhibit a typical S-shaped pattern, which indicates that the α ＋ β→β phase transformation is a nucleation-growth-controlled process. The overall activation energy of the α ＋ β→β transformation of the alloy is 797 kJ·mol^-1. The nucleation and growth mechanism of the α ＋ β→β transformation was also investigated using the non-isothermal Avrami exponent. The Avrami exponent during α ＋ β→β transformation process significantly changes with transformed volume fraction increasing, which indicates that the α ＋ β→β transformation mechanism in the Ti-1300 alloy varies at different sections.

Follicle-stimulating hormone promotes proliferation of cultured chicken ovarian germ cells through protein kinases A and C activation

The study was conducted to investigate the effects of follicle-stimulating hormone (FSH) on embryonic chicken ovarian germ cell proliferation and its possible involvements of protein kinases A (PKA) and C (PKC) pathways.Ovarian cells were treated with FSH alone or in the presence of forskolin (FRSK),PKA inhibitor (H89),PKC activator (PMA) or inhibitor (H7).The germ cell number was counted from micropictures.The immunocytochemistry of proliferating cell nuclear antigen (PCNA) was applied to identify the proliferating cells.The germ cell labeling index (LI) was determined for cell proliferation.The FSH treatment increased the germ cell number,and this stimulating effect was enhanced by FRSK or PMA,but inhibited by H89 or H7 in a dose-dependent manner.Moreover,the PCNA-LI showed parallel changes with germ cell numbers.This study suggests that FSH may stimulate proliferation of cultured chicken ovarian germ cells by activation of both the PKA and PKC signaling pathways.

Forging-microstructure-tensile properties correlation in a new nearβhigh-strength titanium alloy

Microstructures and tensile properties of a newβhigh-strength titanium alloy Ti-5321(Ti-5 Al-3 Mo-3 V-2 Zr-2 Cr-1 Nb-1 Fe)were investigated in this study.Four microstructures,including equiaxed microstructure(EM),bimodal microstructure(BM),basket-weave microstructure(WM)and lamellar microstructure(LM),were tailored by changing the forging process,and the influences of different microstructures on tensile properties were also analyzed.The results indicated that Ti-5321 exhibits a better combination of strength and ductility,compared to Ti-5553,Ti-1023,BT22 and Ti15-3.The ultimate tensile strength,total elongation and reduction in area could be achieved in a range of 1200-1300 MPa,10%-15%and40%-60%,respectively.The influences of variant selection on the tensile properties in Ti-5321 alloy were also analyzed.Afterβforging and solution treatment,αphase maintained strictly Burgers orientation relation with adjacentβphase.Morphological features of the fractography in BM and LM were also explored to further explain the tensile properties and the fracture mode of Ti-5321 alloy.

Physical properties of WSTi3515S burn-resistant titanium alloy

Development of burn-resistant titanium alloys is the most direct way of mitigating the ignition and propagation of titanium fires in jet engines. WSTi3515S alloy（Ti–35V–15Cr–0.3Si–0.1C） is a new high alloying beta type burn-resistant titanium alloy, belonging to Ti–V–Cr type alloys which have been made significant progress in engineering technology in the past 5 years. The physical properties of WSTi3515S burn-resistant titanium alloy such as the elastic properties and thermal properties were measured and analyzed in different conditions. The results show that both the Young＇s modulus and shear modulus of WSTi3515S alloy decrease slightly with the temperature increasing at the tested temperature range. The Poisson＇s ratio of WSTi3515S alloy is around 0.36. However, the thermal properties such as the specific heat, thermal diffusivity, thermal conductivity and thermal expansion increase with the temperature increasing, which results from the strengthening of lattice heat vibration at elevated temperature. And the room temperature density of WSTi3515S alloy is 5.295 gácm^（-3）.