熔铸法制备原位内生Al3Tip/AZ91D复合材料

采用熔铸法制备了Al3Tip体积分数分别为4%和8%的AZ91D复合材料,研究了其显微组织和物相,测试了其致密度、硬度及磨损性能。结果表明,复合材料组织致密,原位内生的Al3Ti颗粒尺寸细小,呈球形且在基体中分布较均匀,与基体结合紧密;随Al3Ti体积分数的增加复合材料的致密度降低,硬度升高,但其耐磨性反而有所降低。与基体AZ91D合金相比,Al3Tip/AZ91D基复合材料的硬度和耐磨性均得到明显提高。     

AZ91D镁合金表面真空扩散渗铝层结构及性能研究

采用真空固态扩散渗铝的方法,在420℃对AZ91D镁合金进行表面合金化改性处理.对渗铝层的组织结构、耐腐蚀性能、显微硬度等进行了研究,测量了该合金扩散渗铝前后试样的电化学腐蚀极化曲线.结果表明,真空固态扩散在AZ91D镁合金表面获得了均匀致密的渗铝层,渗铝层由表及里依次由Al3Mg2最外层,β-Mg17Al12次外层,以及以β-Mg17Al12为主的β-Mg17Al12+α-Mg两相组织内层构成,该渗铝层明显改善了AZ91D镁合金在质量分数5%NaCl溶液中的耐腐蚀性能,并提高了材料的表面显微硬度(1600～1800 MPa).     

压力对挤压铸造Mg-Zn-Y准晶增强AZ91D镁基复合材料显微组织和力学性能的影响(英文)

采用挤压铸造工艺制备Mg-Zn-Y准晶增强AZ91D镁基复合材料,研究挤压压力对此复合材料显微组织和力学性能的影响。研究结果表明:挤压铸造工艺是细化晶粒的有效方法,复合材料由α-Mg基体、β-Mg17Al12相以及二十面体Mg3Zn6Y准晶相(I相)组成,且随着挤压压力的增大,β-Mg17Al12相以及Mg3Zn6Y准晶颗粒含量增加,基体晶粒进一步细化,α-Mg树枝晶向等轴晶转变;当挤压压力为100 MPa时,极限抗拉强度和断后伸长率达到最大值,分别为194.3 MPa和9.2%,拉伸断口出现大量韧窝;准晶增强AZ91D镁基复合材料的强化机制主要为细晶强化和准晶颗粒强化。     

挤压铸造准晶增强AZ91D镁基复合材料组织与性能

为了改善AZ91D镁合金的性能,采用挤压铸造法制备了Mg-Zn-Y准晶中间合金增强AZ91D镁基复合材料,研究了准晶中间合金含量对复合材料组织和性能的影响。结果表明挤压铸造工艺可以有效细化晶粒,复合材料的显微组织主要由α-Mg基体、晶界上分布的β-Mg17Al12相以及Mg3Zn6Y准晶颗粒组成,准晶颗粒和α-Mg基体之间形成稳定结合。当准晶中间合金含量为5%时,抗拉强度和断后伸长率达到最大值,分别为194.3MPa和9.2%。复合材料的强化机制为细晶强化和准晶颗粒强化。     

微量钒对AZ91D镁合金显微组织的影响

研究了添加微量钒对AZ91D镁合金显微组织的影响。在AZ91D镁合金熔炼过程加入AlV55中间合金引入钒元素,用光学显微镜、扫描电镜、能谱仪和X射线衍射等分析研究了加钒前后合金组织的变化以及钒在合金中的存在形式。结果表明:钒的引入使β-Mg17Al12相由不连续网状逐渐离散化,钒在AZ91D合金中主要以新相Al3V形式溶解或分散于β-Mg17Al12相和α-Mg基体中。高熔点的新相Al3V在AZ91D镁合金凝固过程中先于其他相生成聚集在固液界面前沿,抑制晶粒的长大;同时由于α-Mg相细化而使晶界面积增加,相应的单位面积晶界处发生共晶反应的熔液体积减少,生成的β-Mg17Al12相变得细小。同时由于晶粒尺寸减小以及晶界处Al3V相的强化作用,AZ91D合金的硬度随着添加钒含量的增加呈增大趋势。     

挤压铸造AZ91D镁合金的显微组织与力学性能

研究了挤压铸造AZ91D镁合金在不同热处理状态下的显微组织、力学性能以及厚度对镁合金试样力学性能的影响。结果表明,挤压铸造AZ91D镁合金铸态显微组织主要由基体α-Mg和在晶内及晶界上分布的β-Mg17Al12相组成,经固溶处理后得到单相α-Mg固溶体组织,而且在α-Mg晶粒内部也出现了少量颗粒状析出物,经固溶时效处理后β-Mg17Al12相再一次在α-Mg晶内和晶界析出,且晶粒变得更加细小;挤压铸造AZ91D镁合金的硬度、屈服强度、抗拉强度随着试样厚度的增加而减小,而伸长率随着试样厚度的增加而增加。     

AZ91D镁合金等离子束重熔组织与性能(英文)

利用高能等离子束对AZ91D镁合金表面进行快速加热重熔处理,并对重熔层的显微组织、物相、硬度以及耐磨耐蚀性能进行分析。结果表明:在低放大倍数下,重熔层的组织为细小的枝晶,在高放大倍数下,晶粒为细小的等轴晶粒,尺寸为5~7μm;与基体相比,物相组成仍为α-Mg和β-Mg17Al12,但α-Mg相减少,β-Mg17Al12增加,且β-Mg17Al12相的分布更加均匀弥散;重熔层的显微硬度明显高于基体的显微硬度;重熔层拉伸断口与基体拉伸断口不同,有塑性变形痕迹以及由细小均匀韧窝组成的纤维状的撕裂痕,也有明显的晶粒拔出痕迹。等离子重熔处理提高了AZ91D镁合金的表面耐磨性和耐蚀性能。     

微重力磁场对Cu-SiC_p/AZ91D复合材料组织及性能的影响

在常规和电磁模拟微重力条件下制备Cu-SiC_p/AZ91D复合材料,分析了复合材料的组织结构及相组成,并对其组织形成机理和抗摩擦磨损性能进行研究。结果表明,常规条件下制备的Cu-SiC_p/AZ91D复合材料主要由α-Mg、β-Mg_(17)Al_(12)和Mg_2Si相组成,组织晶粒较AZ91D细小,其组织均匀性差;在电磁模拟微重力条件下,Cu-SiC_p/AZ91D复合材料组织转变为α-Mg和Mg_2Si相,组织均匀性显著改善,同时晶粒得到进一步细化,硬度(HV_(4.9))增大至80.46。试验表明,模拟微重力条件制备的Cu-SiC_p/AZ91D复合材料具有更低的摩擦因数和磨损率。     

SiC及Cu-SiC颗粒增强镁基复合材料的制备及性能

利用化学镀法制备了Cu包覆SiCp,研究了SiCp及Cu-SiCp增强镁基复合材料(SiCp/AZ91D和Cu-SiCp/AZ91D)的性能。采用扫描电镜(SEM)、X射线衍射仪及UTM4304电子万能试验机分析测试了镁基复合材料的组织结构,相组成及力学性能。结果表明,SiC颗粒增强镁基复合材料主要由α-Mg和Mg2Si相组成,SiC镀Cu后能够进一步细化晶粒,同时在Mg2Si相周边出现层片状的α+β相。SiCp/AZ91D和Cu-SiCp/AZ91D复合材料的力学性能显著高于AZ91D基体合金,Cu-SiCp/AZ91D复合材料的的抗拉强度达195.7 MPa。室温拉伸时,AZ91D合金表现为典型的脆性断裂特征,而SiCp/AZ91D和Cu-SiC/AZ91D复合材料表现为韧性断裂及部分准解理断裂。     

热处理对Mg2B2O5w／AZ91D复合材料组织及性能的影响

研究了固溶处理和时效处理的Mg2B2o5w/AZ91D镁基复合材料组织与显微硬度之间的关系.结果表明:经过415℃固溶处理后,共晶相的分解使复合材料的硬度明显下降.时效处理使得复合材料的硬度逐渐增加并在时效处理200℃×16h后出现时效峰值201HV,然而随着时效时间的进一步增加,显微硬度降低.经固溶处理415℃×24h,基体中β-Mg17Al12相基本溶解,形成过饱和固溶体,接着时效处理8h,β-Mg177Al12相以弥散形式析出,从而使得复合材料的显微硬度提高30%;而固溶处理415℃×24h,接着200℃时效处理24h后,析出相在形貌上由连续细小析出相向非连续粗大析出相过渡,这使得复合材料的显微硬度下降到183HV.     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

Rheology Feature of Simple Metal Melt

The rheology feature of Sb, Bi melt and alloys was studied using coaxial cylinder high-temperature viscometer. The results showed that the curve of torsion-rotational speed for Sb melt presents a linear relation in all measured temperature ranges, whereas for the Bi melt, the curve presents obvious non-Newtonian feature within the low temperature range and at relative high shear stress. The rheology feature of Sb80Bi20 and Sb20Bi80 alloy melts was well correlated with that of Sb and Bi, respectively. It is considered that the rheology behavior of Sb melt plays a crucial role in Sb80Bi20 alloy and that of Bi melt plays a crucial role in Sb20Bi80 alloy.     

Microstructures and Mechanical Properties of a Newly Developed Austenitic Heat Resistant Steel

The effect of heat treatment on the microstructures and mechanical properties of a newly developed austenitic heat resistant steel(named as T8 alloy) for ultra-supercritical applications have been studied. Results show that the main phases in the alloy after solution treatment are γ and primary MX. Subsequent aging treatment causes the precipitation of M_(23)C_6 carbides along the grain boundaries and a small number of nanoscale MX inside the grains. In addition, with increasing the aging temperature and time, the morphology of M_(23)C_6 carbides changes from semi-continuous chain to continuous network.Compared with a commercial HR3C alloy, T8 alloy has comparable tensile strength, but higher stress rupture strength. The dominant cracking mechanism of the alloy during tensile test at room temperature is transgranular, while at high temperature, intergranular cracking becomes the main cracking mode, which may be caused by the precipitation of continuous M_(23)C_6 carbides along the grain boundaries. Typical intergranular cracking is the dominant cracking mode of the alloy at all stress rupture tests.     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

The 15th Global Foundry Sourcing Conference 2014held in Qingdao China

Organized by Suppliers China Co., Ltd and co-organized by the National Technical Committee 54 on Foundry of Standardization Administration of China, the 15th Global Foundry Sourcing Conference 2014 （hereinafter referred to as FSC 2014） was successfully held on Sep. 23rd in Grand Regency Hotel, Qingdao. More than 500 delegates from home and abroad attended this conference, including over 130 purchasers from 20 countries and 380 domestic and foreign suppliers.     

Secondary Recrystallization Behaviors of Grain-Oriented 6.5 wt% Silicon Steel Sheets Produced by Rolling and Nitriding Processes

By rolling and nitriding processes, 0.23- to 0.3-mm-thick grain-oriented 6.5 wt% silicon steel sheets were produced. The core losses of grain-oriented 6.5 wt% silicon steel at frequencies ranging from 400 Hz to 20 k Hz were lower than that of the grain-oriented 3 wt% silicon steel with the same thickness by 16.6–35.8%. The secondary recrystallization behavior was investigated by scanning electron microscopy, energy-dispersive spectroscopy, and electron backscattered diffraction. The results show that the secondary recrystallization in high-silicon steel sheets develops more completely as the nitrogen content increases after nitriding, secondary recrystallized grain sizes become larger, and the sharpness of Goss texture increases. Because more {110}116 grains in the subsurface and the central layer of the sheets have a lot of 20°–45° high-energy boundaries in addition to Goss grains, {110}116 can be the main component through selective growth during secondary recrystallization when the inhibitor quantity is not enough and inhibitor intensity is weaker. The increases in nitrogen content can increase the inhibitor intensity and hinder abnormal growth of a mount of {110}116 grains and therefore enhance the sharpness of Goss texture.     

Laser Cladded TiCN Coatings on the Surface of Titanium

Laser cladded coatings of TiCN were produced on the surface of titanium. To obtain the optimal techniques, several conditions were tested by varying the laser scanning rate. The choice of shielding gas was also studied. The cladded coatings were then evaluated from the surface mechanics point of view based on their microhardness. The microstructure of some interesting samples was investigated by optical micrographs (OM). The results showed that under the condition of fixed pulse frequency and pulse width, the laser scanning rate and the shielding gas are the main factors influencing the components of coatings. TiCN coatings were decompounded and oxidized during the cladding process in the condition of no shielding gas of N2. X-ray diffraction results indicated that the composite coatings composed of TiCN, TiC, Ti2N, and TiO2 were produced using appropriate techniques. The results indicated that the best condition in terms of the surface microhardness is obtained when the scanning rate is 1.5mm / s, the pulse frequency is 15Hz, the pulse width is 3.0ms, and N2 is chosen as the shielding gas. The microhardness of the composite coatings is about 1331kg · mm - 2, which is about 4 times that of the substrate. The optical micrographs indicated that the cladding zone is made up of TiCN, TiO2, and some interdendritic Ti, but the diffusion zone mainly consists of the dendrites phase, and the cladded depth is about 80?滋m, which is more than 2 times that of the laser nitrided sample. There were no microcracks or air bubbles in the cladded sample, which was cladded using the above optimal techniques.     

Effect of Short-Time Aging on the Pitting Corrosion Behavior of a Novel Lean Duplex Stainless Steel 2002

The effect of short-time aging in the temperature range between 400 and 1000 °C on the pitting corrosion behavior and mechanical property of a novel lean duplex stainless steel(LDSS) 2002 was investigated through the potentiostatic critical pitting temperature(CPT) tests and the Charpy impact tests. Both the pitting corrosion resistance and the toughness of aged specimens degraded due to the precipitation of detrimental secondary phases and the most significant reduction of CPT and impact energy emerged at 650 °C concurrently. The CPT of LDSS 2002 specimen aged at 650 °C decreased by 28 °C, and the impact energy dropped from 69 to 29 J/cm~2 compared with the solution-annealed sample. Transmission electron microscopy characterization showed that the main precipitates in LDSS 2002 were Cr_2N and M_(23)C_6 along the ferrite–austenite grain boundaries.     

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正The Transactions of Nonferrous Metals Society of China,founded in 1991 and sponsored by The Nonferrous Metals Society of China,is published monthly now and mainly contains reports of original research which reflect the new progresses in the field of nonferrous metals science and technology,including mineral processing,extraction metallurgy,metallic materials and heat treatments,metal working,physical metallurgy,powder metallurgy,with the emphasis