超细/纳米W-20Cu复合粉末的液相烧结机制

采用溶胶-喷雾干燥及氢还原工艺制备超细/纳米W-20 Cu复合粉末:将粉末压制成形,在1 340～1 420℃烧结5～180 min,并研究其致密化行为及晶粒长大机制.结果表明:烧结温度对液相烧结致密化起主要作用,W-20Cu复合粉末在液相烧结早期发生了显著的致密化,在1 420℃烧结5 min时,致密度可达到89％以上;随烧结时间的延长,致密度增加,在1 420℃烧结90 min时,相对密度最高,达到99.1％.液相烧结时,W晶粒不断长大并逐渐球化,且其晶粒大小G与时间烧结t符合G3＝G30+kt关系,服从溶解-析出机制.烧结温度对W晶粒长大影响显著,当温度从1 340℃上升到1 420℃时,其晶粒长大动力学系数从1.59×10-2 μm3/min增大到2.47×10-2 μm3/min,这说明液相的形成、颗粒重排、溶解-析出及W晶粒长大使得细晶W-Cu坯体获得近全致密.     

溶胶-喷雾干燥超细/纳米晶W-20Cu复合粉末的烧结行为

采用喷雾干燥-氢气还原法制备超细/纳米晶W-20Cu(质量分数,%)复合粉末,粉末压坯直接从室温推入高温区烧结不同时间后直接取出水淬,研究其烧结致密化和显微组织的变化。结果表明,超细/纳米晶W-20Cu粉末在1000～1200℃烧结时发生迅速致密化。粉末压坯在1200℃烧结60min,其材料致密度已达到96.4%。1420℃烧结90min时致密度达到99%以上。1100～1420℃烧结时其烧结致密化活化能不断减小,从1100℃时的276.3kJ/mol减小到1420℃时的29.1kJ/mol。当温度低于1200℃时,W晶粒长大不明显,当温度超过1300℃时,W晶粒开始有明显长大。随温度的升高W晶粒发生显著球形化,1420℃烧结时发现其晶粒长大符合G3=kt的Ostwald机制,此时晶粒长大动力学系数K仅为0.024μm3/min。     

纳米晶W-Cu复合粉末烧结行为

研究了机械合金化制备的纳米晶W-xCu(x=15,20,25)复合粉末的烧结行为.结果表明,纳米晶W-Cu复合粉末烧结致密化强烈地依赖于烧结温度与烧结时间.当烧结温度从1 150℃提高到1 200℃时,烧结30min后的烧结体相对密度由91%～94%增加到97%～98%;当烧结温度超过1 300℃时,烧结体发生快速致密化,5 min内相对密度即可达到98%左右.研究还发现,W-Cu合金中W晶粒尺寸也强烈地依赖于烧结温度,即烧结温度愈高,W晶粒长大愈显著.当压坯在1 200～1 250℃烧结30 min后,所得到的晶粒度约为300～500 nm,其中经1 200℃烧结时的晶粒尺寸约为300～350 nm.另外,Cu含量增加有利于烧结致密化,并降低W晶粒长大的趋势.     

纳米晶Mo-Cu复合粉末烧结行为的研究

采用溶胶-喷雾干燥-煅烧-氢气还原的方法制备了纳米晶Mo-18Cu、Mo-30Cu、Mo-40Cu复合粉末,研究了纳米晶Mo-Cu粉末的烧结行为以及Cu含量对致密化的影响.结果表明,纳米晶Mo-Cu复合粉末致密化程度高,速度快,在1050～1200 ℃烧结,Mo-30Cu和Mo-40Cu的相对密度可达98%以上,且合金晶粒细小,而Mo-18Cu在1350 ℃以上烧结,相对密度也可达98%以上,但晶粒聚集长大到5 μm左右.研究发现Mo-Cu复合粉末形成了亚稳态的超饱和Mo(Cu)固溶体,随着烧结温度的升高,Cu相逐渐从亚稳态的超饱和Mo(Cu)固溶体颗粒中析出.     

纳米晶WC-10Co复合粉末的烧结致密化行为

研究了机械合金化纳米晶WC-10Co复合粉末的真空烧结致密化行为和一般规律.结果表明:烧结温度的提高和烧结时间的延长有利于样品的烧结致密化过程,在1 275～1 300℃致密化速度快,在1 300℃,15 min左右致密化过程已基本完成;VC、Cr3C2等复合晶粒长大抑制剂含量的增加不利于致密化过程;新型晶粒长大抑制剂A可以更有效地阻碍晶粒长大;纳米晶WC-10Co-0.8VC/Cr3C2-0.2A复合粉末压坯在1375℃,30min烧结条件下,所得的密度为14.48 g/cm3,晶粒尺寸约为180 nm.     

微量Y2O3对细晶W-Ni-Fe粉末烧结行为和显微组织的影响

采用喷雾干燥-热还原的方法制备纳米级93W-4.9Ni-2.1Fe复合粉末和微量稀土掺杂的复合粉末,研究微量稀土掺杂对烧结致密化和晶粒尺寸的影响.结果表明:微量稀土掺杂能有效地降低该复合粉末的晶粒尺寸,并能改善粉末的分散度;纳米级复合粉末在1380～1410℃液相烧结可实现材料的近全致密化,比同种成分的传统钨合金的烧结温度降低了120℃左右,合金的相对密度可达99%以上;但微量稀土掺杂对烧结的致密化有一定的抑制作用;同时微量稀土元素对合金的晶粒尺寸的抑制作用主要发生在液相烧结阶段.     

不同烧结温度下超细合金烧结体的密度、钴磁和晶粒度

本文研究了钴质量分数为10.5%的超细硬质合金在不同的烧结温度下的致密度、钴磁、晶粒长大等方面的变化趋势。研究结果表明:含量为10.5%的超细硬质合金,当烧结温度达到1 350℃时合金已基本致密化;在经典的WC-Co伪二元状态图表明的固相烧结阶段,随着温度升高,钴磁降低,晶粒长大以并合方式为主,可能存在少许的溶解-析出现象;在液相烧结阶段,钴磁达到稳定值后基本不变,晶粒长大以溶解-析出为主。     

Preparation and Properties of W-15Cu Composite by Electroless Plating and Powder Metallurgy

用化学镀和粉末冶金的方法制备出W-15Cu复合材料。首先用化学方法对W粉表面预处理,然后在其表面化学镀铜。得到的复合粉末用图谱进行表征。发现用化学镀的方法制备出的W-15Cu复合粉末纯度非常高,且W颗粒均匀、被Cu致密的包覆着。呈现出包状结构。这种复合粉末表现出优异的压制性能,压坯分别在300, 400, 500, 600 MPa的压制压力下成形。压坯在1250 ℃温度下保温90 min烧结后,从其断口形貌可以发现W颗粒没有明显的长大,且W颗粒表面特征并没有发生改变,仍然表现出预处理后的表面特征。对烧结体的相对密度、硬度、抗弯强度和电导率同样进行了表征     

90W-7Ni-3Fe纳米晶粉末的瞬时液相强化烧结特征

采用机械合金化(MA)制备了晶粒尺寸为8～18 nm的90W-7Ni-3Fe纳米晶粉末(MA粉末).将粉末注射成形,在1 480～1 500℃经3～5 min瞬时液相烧结.结果表明,采用瞬时液相强化烧结可以得到W晶粒为3～8 μm近全致密的细晶钨合金,显微组织为细小的球形W晶粒均匀地连续分布在纤维状粘结相中,烧结坯具有好的拉抻性能.长时间的传统液相烧结使球状W晶粒迅速粗化,而且密度和强度下降,但延伸率反而增加.在MA粉末中添加微量Y2O3后采用瞬时液相烧结,可以使合金抗拉强度提高到1 055 MPa,延伸率提高到16.5%.     

化学镀和粉末冶金法制备W-15Cu复合材料及性能研究（英文）

用化学镀和粉末冶金的方法制备出W-15Cu复合材料。首先用化学方法对W粉表面预处理,然后在其表面化学镀铜。得到的复合粉末用图谱进行表征。发现用化学镀的方法制备出的W-15Cu复合粉末纯度非常高,且W颗粒均匀、被Cu致密的包覆着。呈现出包状结构。这种复合粉末表现出优异的压制性能,压坯分别在300,400,500,600 MPa的压制压力下成形。压坯在1250℃温度下保温90min烧结后,从其断口形貌可以发现W颗粒没有明显的长大,且W颗粒表面特征并没有发生改变,仍然表现出预处理后的表面特征。对烧结体的相对密度、硬度、抗弯强度和电导率同样进行了表征。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

THERMODYNAMICS STUDY ON THE DECOMPOSITION OF CHROMITE WITH KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

INFLUENCE OF HEAT TREATMENT ON DAMPING BEHAVIOUR OF THE MAGNESIUM WROUGHT ALLOY AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Theoretical Analysis for the Motion and Temperature of Melt Droplets in Spray Degassing Process

The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.     

An Easy Way to Quantify the Adhesion Energy of Nanostructured Cu/X(X=Cr,Ta,Mo,Nb,Zr) Multilayer Films Adherent to Polyimide Substrates

An approach based on film buckling under simple uniaxial tensile testing was utilized in this paper to quantitatively estimate the interfacial energy of the nanostructured multilayer films(NMFs) adherent to flexible substrates. The interfacial energies of polyimide-supported NMFs are determined to be *5.0 J/m2 for Cu/Cr, *4.1 J/m2 for Cu/Ta,*2.8 J/m2 for Cu/Mo, *1.1 J/m2 for Cu/Nb, and *1.2 J/m2 for Cu/Zr NMFs. Furthermore, a linear relationship between the adhesion energy and the interfacial shear strength is clearly demonstrated for the Cu-based NMFs, which is highly indicative of the applicability and reliability of the modified models.     

High-Speed Friction Stir Welding of SiC_p/Al–Mg–Si–Cu Composite

A 17 vol% SiCp/Al–Mg–Si–Cu composite plate with a thickness of 3 mm was successfully friction stir welded(FSWed) at a very high welding speed of 2000 mm/min for the first time. Microstructural observation indicated that the coarsening of the precipitates was greatly inhibited in the heat-affected zone of the FSW joint at high welding speed, due to the significantly reduced peak temperature and duration at high temperature. Therefore, prominent enhancement of the hardness was achieved at the lowest hardness zone of the FSW joint at this high welding speed, which was similar to that of the nugget zone. Furthermore, the ultimate tensile strength of the joint was as high as 369 MPa, which was much higher than that obtained at low welding speed of 100 mm/min(298 MPa). This study provides an effective method to weld aluminum matrix composite with superior quality and high welding efficiency.     

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。     

A STUDY OF TEMPERATURE-DEPENDENT VALENCE BOND STRUCTURE OF TITANIUM

On the basis of energy and shape method for the determination of the valence bond (VB) structures of crystal, the valence bond structure of titanium is redetermined at room temperature and calculated in the whole temperature range of 0-1943K. The outer shell electronic distribution of Ti is e_c~(2.9907) · (s_c~(0.4980) d_c~(2.4927)) ef1.0093 in crystal. The temperature dependences of the VB structures of hcp and bcc phases are the same. The VB structures of hcp and bcc phases monotonically increase or decrease with the increase in temperature, but show discontinuous changes at the phase-transformation temperature 1155K.