稀土Y在电解铜及Cu-Cr合金中的分布与微观组织特征

比较研究了稀土Y在电解铜和Cu-Cr合金中的分布情况以及它与Cu中合金元素的相互影响.结果表明稀土在两种合金中均以化合物的形式存在,呈颗粒状分布在晶内,或富集在晶界.能谱分析表明这些颗粒或晶界富集处主要含Cu、Y、O三种元素,而且,两种合金中稀土化合物富集区域所含有这三种元素的原子含量百分比相差不大.在Cu-Cr-Y合金中的共晶组织中几乎不含Y.     

过烧YAG陶瓷晶界的分析

采用固相反应法用不同的烧结速率在1850℃烧结合成过烧钇铝石榴石（YAG）陶瓷，YAG陶瓷晶界形貌随烧结速率的变化而不同。高纯的毋Al2O3和Y2O3原料粉体经高能球磨在1400℃空气中煅烧，生成主相为YAG相的多相粉体化合物。真空烧结YAG陶瓷时烧结速率800℃／h并在1850℃真空烧结4h会使陶瓷中晶粒长大不充分，晶粒与晶粒之间仍保留明显的面接触，陶瓷内部残存大量直径约1μm的气孔，尺寸与可见光波长接近，对透过率的影响大，陶瓷成半透明；在以100~C／h升至1850℃真空烧结4h的YAG多晶陶瓷半透明化，陶瓷晶粒粗大，晶界宽化且保留熔融态凝固，用TEM及EDS确认晶界处存在毋α-Al2O3和钙钛型YAP共晶相。     

铸铁坩锅抗铝融蚀等离子喷涂技术

针对提高化铝用铸铁坩埚抗融蚀寿命的实际问题,选用价格较低、耐高温、抗融蚀性好的Ａｌ２Ｏ３陶瓷材料作为坩埚内壁的工作层,采用等离子喷涂技术来提高其抗融蚀性。但由于Ａｌ２Ｏ３陶瓷涂层的致密性差、结合强度及抗热震寿命低等缺点,不适宜化铝坩埚在７２０℃长时间加温,且液铝呈搅拌行为的工作条件下使用。本文在Ａｌ２Ｏ３喷涂粉末中加入１３％ＴｉＯ２,促使涂层的组织结构发生变化,提高了涂层的结合强度,改善了涂层的致     

Influences of temperature and Sn-addition on microstructural evolution of Ag during FSW

ABSTRACT

The microstructural evolutions of pure Ag and Ag-0.75 wt-%Sn during rapid cooling friction stir welding (FSW) were examined. At the lower welding temperature of FSW conditions, the annealing twinning was highly suppressed and the microstructural evolution was dominated by the discontinuous dynamic recrystallisation (DDRX) via the high angle boundary (HAB) bulging. The fully recrystallised microstructure was remarkably finer than that formed through the frequent annealing twinning at the higher welding temperature. Moreover, the Sn-addition caused the HAB bulging due to the inhibition of dynamic recovery and decreased mobility of grain boundaries. With decreasing the ratio of the peak temperature to the recrystallisation temperature, the dominant grain refinement mechanism is implied to change from the annealing twinning to the DDRX.     

On the induction plasma deposition of tungsten metal

The central particle injection and long residence time characteristics of induction plasma have given rise to the complete melting of tungsten particles injected into an Ar- H₂ plasma under soft vacuum conditions. The influences of process variables such as power level, chamber pressure, and spray distance on splat morphology, apparent density, and deposition efficiency have been studied. Dense tungsten deposits with no oxidation have been obtained. Scanning electron microscopy (SEM) micrographs reveal a well-flattened lamellar structure in deposits. Radiative cooling is observed to play a significant role in the plasma spraying of this refractory metal.     

压铸模特征参数化实体建模技术的研究

对压铸模智能CAD系统中特征参数化实体建模技术进行了研究。在模型分解技术的基础上，采用特征化和参数化技术建立压铸模零件的实体模型。基于临时模型库、共享模型库和参数化模型库建立参数化实体图形库。基于确定零件装配关系的数据结构生成参数化的压铸模实体装配图。该技术在实际应用中取得了很好的效果，成为压铸模智能化设计的重要组成部分。     

Microstructure and tribological properties of Cuss-toughened Cr–Cu–Si metal silicide alloys

Wear resistant Cr–Cu–Si metal silicide alloys with different Cu contents were fabricated by the laser melting process. The Cr–Cu–Si alloys have a similar microstructure consisting of the Cr₅Si₃/CrSi dual-phase primary dendrites and the interdendritic Cu-based solid solution (Cu_ss). The Cu content has no effect on the phase constitutions of the alloys. The Cr₅Si₃/CrSi dendrite volume fraction and hardness of the Cr–Cu–Si alloys decrease with the increasing Cu content. Wear test results indicate that all the Cu_ss-toughened metal silicide alloys have excellent wear resistance and low coefficient of friction. Wear resistance increases and friction coefficient decreases with the decreasing Cu content.     

熔铸法制造采煤机截齿的研究

介绍了熔铸法制造截齿的基本过程。所制截齿热处理后，沿粉末圆柱体齿头横截面上的硬度分布为：中心ＨＲＣ６８，过渡区６２，基体５５；结合层牢固，截齿的使用寿命增加。     

电弧加热器环境下双连续TiB2-（Cu，Ni）复合材料的发汗冷却行为

采用粉末烧结结合浸渗法制备高体积TiB2含量的双连续81．6％TiB2／（Cu，Ni）复合材料，并利用扫描电镜（SEM）、透射电镜（TEM）和物相测定（XRD）对连续复合材料的微观组织形貌进行了观测，表明复合材料中陶瓷骨架相和金属相在各自空间均形成三维网络结构且界面结合牢靠。用交流等离子电弧加热器对试件表面瞬时加热来考核复合材料的抗热冲击和抗烧蚀行为。结果表明，材料在电弧急剧加热和冷却过程中均没有出现“热裂”现象，烧蚀后材料的微观组织分析表明，金属（Cu，Ni）相在材料烧蚀区-过渡区-基体区存在明显的梯度分布，分析了高温下金属相“发汗冷却”行为和防热机理。     

N80钢管在线常化强化作用研究

利用金属物理实验方法，研究了在线常化工艺对Ｎ８０钢管组织和性能的影响。结果表明，在线常化工艺可以在适当减小强度值的情况下大幅度提高钢管的冲击韧性，尤其可使微合金化钢获得较好的强韧化效果。