新型热处理方法制备超高强度Inconel 718合金

为改善Inconel718合金的组织并优化性能,提出一种980℃,1 min高温超短退火和随后的双时效相结合的新型热处理方法。结果表明,超短退火处理产生了部分再结晶组织,KAM图表明即使在变形晶粒中也形成了再结晶晶核。因此,高温超短退火克服了再结晶势垒,使得后续的再结晶过程可以在较低温度的时效处理过程中完成,从而获得了均匀细化的组织(~3.59μm)。980-1min-aged样品具有优异的拉伸性能,室温极限强度和总伸长率分别为1600 MPa和19%。650℃热拉伸条件下的极限强度和伸长率分别约为1350 MPa和26%。因此,高温超短退火能有效提高Inconel718合金的性能。

Effect of annealing temperature on microstructure and mechanical properties of cold-rolled commercially pure titanium sheets

The strength of traditional commercially pure titanium(CP-Ti) alloys often fails to meet the demand of structural materials. In order to enhance their mechanical properties, the cold-rolled CP-Ti alloys were annealed at different temperatures, and the recrystallization behavior and texture evolution were investigated. It was found that the bimodal microstructure(equiaxed and elongated grains) was formed after partial recrystallization, and the corresponding sample exhibited an excellent combination of ultimate tensile strength(702 MPa) and total elongation(36.4%). The recrystallization nucleation of CP-Ti sheets occurred preferentially in the high strain and the high-angle grain boundaries(HAGBs) regions. Meanwhile, the internal misorientations of the deformed heterogeneous grains increased and transformed into HAGBs, which further promoted the recrystallization nucleation. The main recrystallization texture was basal TD-split texture transformed from cold-rolled basal RD-split texture, and the oriented nucleation played a dominated role during recrystallization.

Influence of heat treatment on microstructure and nanohardness of TiAl alloy solidified under high pressure

The Ti-48at.%Al alloy solidified under different pressures was prepared using a tungsten-carbide six-anvil apparatus and then heat treated at different temperatures.The effect of heat treatment on microstructure and mechanical properties of high pressure solidified Ti-48Al alloy was investigated.The results showed that the phase constitution of the Ti-48Al alloy solidified under high pressure did not change after heat treatment.After 1,100℃/12 h AC(air cooling),the value of c/a showed a slight increase.The Widmanst?tten structure was formed in the samples solidified under 2 GPa and 4 GPa.More defects were found in the high-pressure samples.The volume fraction ofα2 particles increased with an increase in pressure.After 1,150℃/4 h AC,the discontinuous coarsening phenomenon could only be found in the 4 GPa solidified samples.The formation ofα2 phase can lead to the increase of nanohardness.Compared with the samples before heat treatment,the nanohardness increased about 1.0-1.2 GPa.

Effect of dl-3-n-butylphthalide on infarction volume in animal models of ischemic stroke:A meta-analysis

BACKGROUND Ischemic stroke is a frequently-occurring disease in the elderly and characterized by high morbidity and mortality.Dl-3-n-butylphthalide(NBP),a synthetic compound based on natural celery seeds,has potential therapeutic effects on cerebral ischemia,brain trauma,memory impairment,and epilepsy.AIM To evaluated the effect of NBP on infarct volume in experimental ischemic stroke.METHODS Twenty one relevant literatures were included from the PubMed,EMBASE,Web of Science,Chinese National Knowledge Infrastructure,VIP information database,and Wanfang database,and data on the effect of dl-3-n-butylphthalide on infarction volume in the middle cerebral artery occlusion model were extracted.Statistical analysis was performed using standard mean difference with random effects model of Revman 5.3.RESULTS The data of meta-analysis of the 21 studies had suggested that NBP reduced the cerebral infarction volume of middle cerebral artery occlusion model animals compared to the control group significantly[SMD:-3.97,95%CI:-4.71 to-3.23,P<0.01;heterogeneity:χ2=59.09,df=20(P<0.01);I2=66%].CONCLUSION NBP was effective in experimental ischemic stroke.

The regulatory variant rs17612742 confers the risk of large artery atherosclerotic stroke by increasing the expression of endothelin receptor type A

Genome-wide association studies have found that rs17612742 increases the risk of large artery atherosclerotic stroke.The rs17612742 was located in the intron region of Endothelin receptor type A(NRA),which was cellular and gender-heterogeneous.Functional genomics studies of rs17612742 were carried out through some public databases,and it was found that rs17612742 was located in the chromatin open region and promoted the expression of NRA.Compared with the control group,EDNRA expression increased in middle cerebral artery occlusion exposed rodents.However,age heterogeneity of EDNRA expression under physiological and pathological conditions was not observed.In addition,we also discussed how to conduct further empirical studies to provide evidence that rs17612742 confers the risk of large artery atherosclerotic stroke by increasing the expression of NRA.

Characterization of Microstructure and Texture in Grain-Oriented High Silicon Steel by Strip Casting

Grain-oriented 4.5 wt% Si and 6.5 wt% Si steels were produced by strip casting, warm rolling, cold rolling, primary annealing, and secondary annealing. Goss grains were sufficiently developed and covered the entire surface of the secondary recrystallized sheets. The microstructure and texture was characterized by OM, EBSD, TEM, and XRD. It was observed that after rolling at 700 ℃, the 6.5 wt% Si steel exhibited a considerable degree of shear bands, whereas the 4.5 wt% Si steel indicated their rare presence. After primary annealing, completely equiaxed grains showing strong y-fiber texture were presented in both alloys. By comparison, the 6.5 wt% Si steel showed smaller grain size and few favorable Goss grains. Additionally, a higher density of fine precipitates were exhibited in the 6.5 wt% Si steel, leading to a ~ 30-s delay in primary recrystallization. During secondary annealing, abnormal grain growth of the 6.5 wt% Si steel occurred at higher temperature compared to the 4.5 wt% Si steel, and the final grain size of the 6.5 wt% Si steel was greater. The magnetic induction B8 of the 4.5 wt% Si and the 6.5 wt% Si steels was 1.75 and 1.76 T, respectively, and the high- frequency core losses were significantly improved in comparison with the non-oriented high silicon steel.