Thermodynamics and kinetics analysis of in-situ synthesizing AIN

AIN powders were prepared by in-situ synthesis technique. It is a reaction of binary molten Al−Mg alloys with highly pure nitrogen. It was confirmed through thermodynamics calculation that Mg element in Al−Mg alloys can decrease oxygen content in the reacting system. Thus, nitridation reaction can be performed to form AIN. Moreover, an analysis of kinetics shows that the nitridation reaction of Al−Mg alloys can be accelerated and transferred rapidly with the increment of Mg content.     

Effects of Mg content on pore structure and electrochemical corrosion behaviors of porous Al-Mg alloys

Porous Al-Mg alloys with different nominal compositions were successfully fabricated via elemental powder reactive synthesis, and the phase composition, pore structure, and corrosion resistance were characterized with X-ray diffractometer, scanning electron microscope and electrochemical analyzer. The volume expansion ratio, open porosity and corrosion resistance in 3.5%(mass fraction) Na Cl aqueous solution of the alloys increase at first and then decrease with the increase of Mg content. The maxima of volume expansion ratio and open porosity are 18.3% and 28.1% for the porous Al-56%Mg(mass fraction) alloy, while there is the best corrosion resistance for the porous Al-37.5% Mg(mass fraction) alloy. The pore formation mechanism can be explained by Kirkendall effect, and the corrosion resistance can be mainly affected by the phase composition for the porous Al-Mg alloys. They would be of the potential application for filtration in the chloride environment.     

直接氧化法制备Al2O3/Al陶瓷基复合材料研究

研究了采用直接氧法制备Ａｌ２Ｏ３／Ａｌ复合材料,实验分析了镁元素对铝氧化的决定因素和硅对氧化速度的影响,通过Ｘ－线衍射对烧结材料进行物相分析,光镜观察烧结材料的结构是三维联通的三氧化二铝瘊多晶体中分布了三维联通的网状的残余铝合金。     

SiO2/Al-Mg复合材料的界面反应

对粉末冶金法制备的SiO2/Al-Mg复合材料的显微组织、物相组成及反应过程进行了研究,发现10%~20%SiO2-Al-Mg复合材料的最终物相均为MgAl2O4、MgO、Mg2Si、Si和Al.反应时Al、Mg由SiO2颗粒外向颗粒内扩散,SiO2被夺去氧,Si被置换到原SiO2颗粒外.总结了颗粒SiO2与Al-Mg反应的热力学,推测了颗粒内外的优先反应.     

Effect of magnesium and nickel coatings on the wetting behavior of alumina toughened zirconia by molten Al-Mg alloy

The wettability of alumina toughened zirconia (ZTA) by Al-Mg alloy was investigated using the sessile drop technique. The effects of nickel coating, magnesium content, nitrogen atmosphere, and processing temperature on the contact angle between the molten alloy and the substrate were determined. Likewise, the effect of these factors on the wetting properties was studied. The results showed that the nickel coating on the ceramic substrate caused a significant reduction in solid/liquid surface energy and the contact angle decreased obvi-ously. The presence of magnesium in the molten aluminum alloy in nitrogen atmosphere reduced the contact angle effectively. The presence of magnesium in the alloy must be at a minimum amount of 2wt%-3wt%. Moreover, it was suggested that some chemical reactions in the Al-Mg-N system led to the production of Mg3N2 and AlN compositions. These compositions improved the wetting properties of the systems by reducing the surface energy of the molten. It was shown that increasing the temperature is also an effective factor for the enhancement of wetting properties.     

氮化铝体单晶生长技术研究进展(英文)

评述氮化铝体单晶生长技术中常用的金属铝直接氮化法、溶解生长法、氢化物气相外延法和物理气相传输法.指出氢化物气相外延法和物理气相传输法是前景看好的生长氮化铝体单晶方法.介绍本课题组对物理气相传输法的一些改进.认为生长大尺寸氮化铝单晶体的研究将集中在精确控制生长条件、选择合适的坩埚材料、优化制备工艺和制备优质氮化铝籽晶等方面.     

铝镁合金脱氧理论研究

分析了铝、镁及铝镁合金作为炼钢脱氧、脱硫剂的应用现状 ,并从热力学上探讨了铝镁合金脱氧、脱硫、去除钢中夹杂的优越性 .铝镁合金是一种性能优异的脱氧、脱硫、钢液纯洁剂 ,在钢液的还原精炼方面具有广阔的应用前景     

Influence of Mg3N2 powder on microstructures and mechanical properties of AZ31 Mg alloy

In order to obtain an effective and reliable grain refiner for Mg-Al alloys, 1% （mass fraction） Mg3N2 was added into AZ31 Mg alloy. The microstructures of the Mg alloys were studied by optical microscopy, scan electron microscopy and X-ray energy dispersive spectroscopy, and the mechanical properties were determined. The results show that adding a small amount of Mg3N2 to AZ31 Mg alloy can refine the grain size from 103 to 58 μm. The ultimate tensile strength and elongation of AZ31 Mg alloy are 174.1MPa and 8.3%, respectively. After the addition of 1% Mg3N2, the ultimate tensile strength and elongation of AZ31 Mg alloy are increased up to 198.7 MPa and 11.8%, respectively. The grain refinement mechanism is that AIN is formed after Mg3N2 is added. Both AIN and Mg phases are of HCP lattice structure, and the disregistry between Mg phases and AIN along （0001）Mg//（0001）AIN is 3.04%, which is very effective for heterogeneous nucleation.     

反应烧结制备AlN陶瓷的机理研究

以 Al、Al N粉为原料 ,采用反应烧结技术制备 Al N陶瓷。用 XRD、SEM和 TG/ DSC等手段分析了反应烧结过程 ,提出了反应烧结机理。 Al粉的氮化在不同温度范围受不同过程控制 ,为逐步氮化机制 ,Al的颗粒尺寸影响着氮化行为     

Influence of Mg2N2 powder on microstructures and mechanical properties of AZ31 Mg alloy

In order to obtain an effective and reliable grain refiner for Mg-Al alloys, 1% (mass fraction) Mg3N2 was added into AZ31 Mg alloy. The microstructures of the Mg alloys were studied by optical microscopy, scan electron microscopy and X-ray energy dispersive spectroscopy, and the mechanical properties were determined. The results show that adding a small amount of Mg3N2 to AZ31 Mg alloy can refine the grain size from 103 to 58 μm. The ultimate tensile strength and elongation of AZ31 Mg alloy are 174.1MPa and 8.3%, respectively. After the addition of 1% Mg3N2, the ultimate tensile strength and elongation of AZ31 Mg alloy are increased up to 198.7 MPa and 11.8%, respectively. The grain refinement mechanism is that AIN is formed after Mg3N2 is added.Both A1N and Mg phases are of HCP lattice structure, and the disregistry between Mg phases and AIN along (0001)Mg//(0001)AlN is 3.04%, which is very effective for heterogeneous nucleation.     

压铸态Mg8%Al-xNd合金的低周疲劳行为

为了确定稀土元素Nd对Mg8%Al系压铸镁合金低周疲劳行为的影响规律,在不同外加总应变幅下针对压铸态Mg8%Al-xNd进行了应变控制的室温疲劳试验.结果表明,低周疲劳加载条件下,压铸态Mg8%Al-xNd镁合金可表现为循环应变硬化和循环稳定,主要取决于外加总应变幅的高低以及Nd的质量分数;适量稀土元素Nd的添加可有效提高压铸态Mg 8%〖KG-*5〗Al系合金的疲劳寿命;压铸态Mg8%Al-xNd合金的弹性应变幅、塑性应变幅与疲劳断裂时载荷反向周次之间的关系可分别用Basquin和Coffin Manson公式描述.疲劳断口形貌观察结果表明,对于压铸态Mg8%Al-xNd合金,低周疲劳裂纹均是以穿晶方式萌生并以穿晶方式扩展的.     

Electrodeposition of aluminum and aluminum-magnesium alloys at room temperature

Electrodeposition of aluminum from benzene-tetrahydrofuran-Al Cl3-Li Al H4 was studied at room temperature. Galvanostatic electrolysis was used to investigate the effect of various parameters on deposit morphology and crystal size, including current density, temperature, molar ratio of benzene/tetrahydrofuran and stirring speed. The deposit microstructure was adjusted by changing the parameters, and the optimum operating conditions were determined. Dense, bright and adherent aluminum coatings were obtained over a wide range of current densities(10-25 m A/cm2), molar ratio of benzene and tetrahydrofuran(4:1 to 7:8) and stirring speeds(200-500 r/min). Smaller grain sizes and well-adhered deposits were obtained at lower temperatures. Aluminum-magnesium alloys could potentially be used as hydrogen storage materials. A novel method for Al-Mg deposition was proposed by using pure Mg anodes in the organic solvents system benzene-tetrahydrofuran-Al Cl3-Li Al H4. XRD shows that the aluminum-magnesium alloys are mainly Al3Mg2 and Al12Mg17.     

Mg-Zn-Ca非晶合金对酸性红偶氮颜料的降解能力

为了有效降低酸性红偶氮颜料废水对环境的危害,研究了Mg-Zn-Ca合金的非晶形成能力与非晶条带的循环使用次数对废水的降解速率和脱色率的影响.结果表明,当x不大于4时,M g71+xZn24-xCa5合金可以形成非晶条带.降解速率和脱色率随非晶条带中Mg含量的增加而提高,Mg71Zn24Ca5、Mg73Zn22Ca5和Mg75Zn20Ca5合金与废水作用1 h后的脱色率分别达到83.56%、85.75%和87.18%.脱色反应前后非晶条带的结构基本不变,表明非晶合金具有循环使用特征.非晶合金中Ca元素可以优先富集形成矿化物质,从而造成Mg元素在合金表面的富集,这成为非晶合金的降解能力并未显著降低的主要原因.     

一种合成AlN粉末的新方法

研究了气氛对Ａｌ２Ｏ３与ＢＮ在高温下反应形成ＡｌＮ的影响，发现在Ｎ２气中Ａｌ２Ｏ３与ＢＮ的应形成了ＡｌＮ的速度很慢，但在Ａｒ气中Ａｌ２Ｏ３与ＢＮ反应形成ＡｌＮ的速度较快，据此提出了一种合成ＡｌＮ的新方法。     

基于RHEED图像外延GaN基薄膜表面晶格演变分析

通过阐述外延薄膜进行原位监测的反射高能电子衍射(RHEED)以及RHEED图像的条纹或点阵与GaN基薄膜表面形貌的关系,提出了基于RHEED图像分析外延GaN基薄膜晶体结构演变情况,从衬底α-Al2O3的氢氮等离子体清洗、氮化、生长缓冲层以及生长外延层进行具体的分析、比较和演算.结果表明衬底在清洗前后表面晶格常数基本保持一致,对于氮化层、缓冲层以及外延层情况,表面原子层处于应变状态.     

铸造镁合金的晶粒细化研究进展

介绍了铸造镁合金晶粒细化方面最近的研究进展,指出Al2RE颗粒是有效的形核剂,可用来细化镁-稀土合金和含Al镁合金。其在镁合金中的广泛应用还有待进一步研究。     

Effect of Mg and Si on infiltration behavior of Al alloys pressureless infiltration into porous SiCp preforms

The effect of Mg and Si additon to Al matrix on infiltration kinetics and rates of Al alloys pressureless infiltration into porous SiCp preform was investigated by observing the change of infiltration distance with time as the Al alloys infiltrate into SiCp preforms at different temperatures.The results show that infiltration of SiCp preforms by Al melt is a thermal activation process and there is an incubation period before the infiltration becomes stable.With the increase of Mg content in the Al alloys fr...     

硼及快淬工艺对La-Mg-Ni系贮氢合金的微观结构及电化学容量的影响

用铸造及快淬工艺制备了La-Mg-Ni系(PuNi3型)贮氢合金La2Mg(Ni0.85Co0.15)9Bx(x=0,0.05,0.1,0.15,0.2),分析测试了铸态及快淬态合金的微观结构与电化学容量,研究了硼及快淬工艺对合金微观结构及电化学容量的影响.结果表明,铸态合金具有多相结构,包括(La,Mg)Ni3相(PuNi3型)、LaNi5相,一定量的LaNi2相和微量的Ni2B相,经快淬处理后Ni2B相消失.硼的加入对铸态及快淬态合金的容量产生不同的影响,铸态合金的容量随硼含量的增加而单调下降,而快淬态合金的容量随硼含量的增加有一极大值.快淬处理对含硼及不含硼合金的容量也有不同的影响,随淬速的增加,不含硼合金的容量单调下降,而含硼合金的容量可以获得一个极大值.     

微量Ni对MgNi合金组织与性能的影响

在铸态情况下,研究了添加微量Ni对MgNi合金的微观组织、力学性能、硬度及断裂方式的影响.结果表明,纯Mg的组织主要为α相,MgNi系列合金MgNi0.28,MgNi0.99,MgNi1.54合金除了α固溶体外,还存在γ相和Ni相.纯Mg的晶粒粗大,加入Ni后,晶粒得到细化,大小趋向均匀.当添加少量Ni时,合金的抗拉强度显著增加;但当Ni含量超过0.28%时,抗拉强度增加不明显.随Ni含量的增加,MgNi合金的延伸率、硬度先增大后减小;MgNi合金的断裂方式由解理断裂向沿晶断裂方向发展.     

Effect of magnesium and nickel coatings on the wetting behavior of alumina toughened zirconia by molten Al-Mg ahoy

The wettability of alumina toughened zirconia (ZTA) by Al-Mg alloy was investigated using the sessile drop technique.The effects of nickel coating,magnesium content,nitrogen atmosphere,and processing temperature on the contact angle between the molten alloy and the substrate were determined.Likewise,the effect of these factors on the wetting properties was studied.The results showed that the nickel coating on the ceramic substrate caused a significant reduction in solid/liquid surface energy and the contact angle decreased obviously.The presence of magnesium in the molten aluminum alloy in nitrogen atmosphere reduced the contact angle effectively.The presence of magnesium in the alloy must be at a minimum amount of 2wt％-3wt％.Moreover,it was suggested that some chemical reactions in the Al-Mg-N system led to the production of Mg3N2 and A1N compositions.These compositions improved the wetting properties of the systems by reducing the surface energy of the molten.It was shown that increasing the temperature is also an effective factor for the enhancement of wetting properties.