HOMOGENIZATION TREATMENT OF Mg-Al-Zn(MM)MAGNESIUM ALLOY INGOTS

The Mg-Al-Zn series AZ31 and AZ31 MM alloys are homogenized at 673, 723 and 753K respectively. The hardness of alloy ingots at different heat-treated states is measured and the micro structures are observed. The optimum annealing temperature is 723K and the time is 12h.     

A1-Li合金的拉伸断裂过程研究

以2090 Ce合金为研究对象，对不同时效时间的室温拉伸断口进行了半定量分析，探讨了拉伸性能对断裂特征的响应关系，重点分析合金分层裂纹的形成过程。研究表明：2090 Ce合金的断裂方式以韧窝、分层开裂和沿亚晶界开裂3种为主，随时效时间的延长，韧窝、分层开裂逐渐减少，沿亚晶界开裂比例逐渐加大：分层开裂程度与时效程度有密切关系：分层开裂过程与试样内部受力状态、晶界状态有密切关系。分层最先发生在试样中心，随后在二分之一、四分之一……处反复发生，最终将试样分割成一系列平行的薄板。时效后期由于亚晶界的弱化，使裂纹倾向沿亚晶界扩展，从而抑制分层开裂的发生，同时导致合金强度，尤其是塑性的下降。     

镁合金与钛合金的瞬间液相扩散焊

为实现镁合金AZ31B与钛合金Ti6A14V的可靠连接，研究了两者以Al为中间层的瞬间液相扩散焊接头的微观结构与连接强度。研究结果表明：当焊接时间为180min时，焊接温度是影响界面反应热力学与动力学的主要参数，其对接头的微观组织、接头界面新生相构成与连接强度有重要影响。保温温度低于450℃时，AZ3IB／AI界面无液相产生，无法实现AZ31B与Ti6A14V的可靠连接；保温温度在450℃～480℃变化时，温度对AZ31B／Al／Ti6A14V界面反应的动力学因素有明显影响，且直接决定了焊后接头新生相的构成与分布。470℃保温180min的接头剪切强度较高（72．4MPa），达到AZ31B母材（86MPa）的84．2％。     

采用稀土贮氢材料的镍氢电池

介绍了镍-金属氢化物电池的特性和该类电池所用的稀土贮氢材料及其成份配制、制备工艺、合金添加剂对LaNi_5基合金电极综合性能的影响,以及该类电池的应用开发前景。     

Ti—Al二元合金的成分对组织和力学性能的影响

用金相、扫描电镜和X射线衍射研究了6种不同Al含量Ti-Al二元合金铸态和退火态的组织结构和相组成的特征和变化。从结晶动力学的观点,分析了合金的结晶凝固过程。采用三点弯曲方法研究了合金的抗弯性能同Al含量的关系。结果表明,Al含量为34 wt%,经1100℃/30 h退火的合金抗弯性能最好,Al含量偏离34wt%,都对合金的力学性能不利。     

快速凝固Mg94.6Zn4.8Y0.6镁合金薄带的组织与性能

采用单辊快速凝固技术制备了Mg94.6Zn4.8Y0.6合金薄带,研究了薄带的组织及性能特征。结果表明:Mg94.6Zn4.8Y0.6镁合金快速凝固薄带组织由过饱和的单相-αMg固溶体组成,沿厚度方向分为两个晶区:近辊面粗大等轴晶区和自由面细小等轴晶区。Mg94.6Zn4.8Y0.6合金快速凝固薄带的显微硬度为85.95HV,在250℃左右保温2 h的显微硬度最高,超过该温度(250~300℃)显微硬度显著下降。     

Effect of temperature on mechanical behavior of AZ31 magnesium alloy

Strain rate sensitivity and tension/compression asymmetry of AZ31 magnesium alloy at different temperatures and strainrates were investigated.Both of mechanical behaviors are temperature dependent.Strain rate sensitivity increases with increasingtemperature.Thermally activated slip is the source of strain rate sensitivity.At the temperature below or near 373 K,strain ratesensitivity is very little.Tension/compression asymmetry in yielding decreases with increasing temperature.Twinning is the reasonof tension/compression asymmetry.At the temperature above or near 573 K,the material shows little tension/compressionasymmetry of the flow stress.     

High-temperature corrosion and creep of Ni-Cr-Fe alloys in carburizing and oxidizing environments

The carburization of NiCr 32 20 and NiCrSi 60 16 has been studied in CH₄-H₂ mixtures in the temperature range 900–1100°C. The methods included thermogravimetric measurements and studies on reacted specimens by X-ray diffraction, metallographic, and chemical analysis. Upon carburization internal carbides M₇C₃ and M₂₃C₆ are formed (M=mainly Cr); the rate of carburization is determined by carbon diffusion in the Fe-Ni matrix with carbide precipitations. The effect of the alloying elements Ni and Si on the carburization resistance of austenitic alloys is explained. By the same methods the oxidation and carburization in CO-H₂O-H₂ mixtures have been studied. The important role of a stable chromium oxide layer for the carburization resistance was confirmed. Creep tests at 1000°C in a CO-H₂O-H₂ atmosphere where Cr₂O₃ is stable showed carburization occurring through cracks in the oxide layer. At high strain rates premature failure occurs by carburization, which is followed by internal oxidation and formation of cracks, voids, and holes.     

吹喷氧化物质点改善铁基合金的高温耐磨性

为了节省能源,国内外广泛开展了煤的流化床燃烧技术的研究。然而,流化床中埋管材料及其上面所焊鳍片材料耐高温磨蚀性能的提高,是推广这一技术的关键。采用共沉法或机械合金化方法已成功地制成氧化物弥散强化高温合金,不仅高温强度可以维持到合金的熔点附近,而且可以改善高温耐磨性,但这类合金制造工艺复杂、成本高,不适宜大量用于能源工业。向钢水中吹喷氧化物质点可以明显提高镇静钢的室温和高温强度,而且价     

Borides at interfacial zone of IC6 TLP bonded joints

1　INTRODUCTIONTransientliquidphase (TLP)bondingtechniquehasbeensuccessfullyusedinjoiningheatresistantal loys ,likeHastelloyX ,Inconel713C ,In10 0 ,Udimet5 0 0 ,70 0 ,MarM 2 0 0 ,0 0 7,2 4 7,30 2 ,Rene′80 ,TD NiCr ,MA75 4,6 0 0 0 ,PWA14 2 2 ,CSMX 2etc ,whicharesusceptibletohotcrackingor post weldheat treatmentcrackingproblemsduringfusionweld ing[14 ] .Inaddition ,therewerereportsofjoiningNiAlandTiAlintermetallicsbyTLPbondingmethod[510 ] .Forexample ,Galehadinvestigatedthemic…