原料加入温度对Al-Ti-C晶粒细化剂显微组织的影响

采用K2TiF6、石墨粉和纯铝为主要原料的原位反应方法制备了Al-Ti-C晶粒细化剂.通过光学显微镜、扫描电镜和能谱分析等方法分析了Al-Ti-C中间合金的显微组织.试验结果表明,K2TiF6和石墨粉同温下加入时,Al3Ti呈块状分布,不同温度下加入时则呈针状或长条状分布.随着K2TiF6和石墨粉加入温度的不同,Al-Ti-C中间合金中TiC粒子的生成机制也不同.     

Mg-Sr牺牲阳极显微组织和电化学性能的研究

研究了Mg-Sr牺牲阳极的显微组织和电化学性能的特征.结果表明,Mg-Sr牺牲阳极的晶粒尺寸随Sr含量的增加而减小;当Sr质量分数为0.19%时,电流效率达到58.56%,开路电位达到-1.735 VSCE;Sr的质量分数再增加,Mg-Sr阳极的电流效率降低,开路电位正移.研究认为,Sr的质量分数为0.19%时,晶界析出的Mg17Sr2相（弱阴极相）和α-Mg基体（阳极相）组成电偶对,阻碍了阳极晶间腐蚀,减少了晶粒大块脱落, 且Sr能够和Mg、Fe形成弱阴极性化合物降低Fe的危害,电流效率升高,同时晶粒细化,晶界面积变大,杂质相分布更均匀,开路电位负移;Sr含量大于0.19%时,过量的Mg17Sr2相作为阴极相加大了阳极的自腐蚀,电流效率下降,开路电位正移.     

Role of deposition parameters on microstructure and mechanical properties of chromium oxide coatings

Chromium oxide coatings were deposited by reactive magnetron sputtering on high speed steel (HSS) substrate under various oxygen flow rates and radio frequency (RF) powers. The effect of deposition conditions on the microstructure, hardness and critical load of chromium oxide coating failure was studied. The results indicated that a crystalline chromium oxide coating formed at a high oxygen flow rate and a low RF power exhibited a higher hardness and a lower critical load as compared to a chromium oxide coating with an amorphous microstructure.     

微量Nb、V对高强度耐候钢组织与性能的影响

对低碳的0.4Cu-0.07P-0.6Cr-0.3Ni高强度耐候钢分别添加0.026%Nb或0.073%V后,进行同一轧制工艺试验和正火处理,结果发现含Nb钢比含V钢塑韧性高但强度低,且组织更易发生岛状马氏体或粒状贝氏体转变。     

Properties and Microstructuresof Three Kinds of Silversheathed Bi-2223 Tapes

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In situ technique for synthesizing multiple ceramic particulates reinforced titanium matrix composites (TiB + TiC + Y2O3)/Ti

In situ synthesized titanium matrix composites reinforced with multiple ceramic particulates including TiB, TiC and Y₂O₃ were fabricated by non-consumable arc-melting technique utilizing the chemical reaction among Ti, B₂O₃, B₄C and Y. The thermodynamic feasibility of the in situ reactions has been considered. X-ray diffraction (XRD) was used to identify the phases in the composites. Microstructures of the composites were observed by means of optical microscope (OM), scanning electron microscope (SEM) and electron probe. It is concluded that multiple reinforcements are synthesized and they show different shapes: TiB grows in needle shape; TiC grows in near-equiaxed and rod-like shapes; Y₂O₃ grows in near-equiaxed shapes when the content of Y is 0.6 wt.% and grows in dendritic shapes when the content of Y increases to 1.8 wt.%. Reinforcements TiB, TiC and Y₂O₃ are distributed uniformly in the titanium matrix.     

Tensile behavior change depending on the varying tungsten content of W–Ni–Fe alloys

Tungsten heavy alloys (WHAs) are metal–metal composites consisting of nearly pure spherical tungsten particles embedded in a Ni–Fe–W or Ni–Co–W or Ni–Cu–W ductile matrix. In this dual phase alloy, there are several complicated relations between the ductile matrix and hard tungsten particles. The aim of this research was to examine the effect of varying tungsten content on the microstructure and mechanical properties of tungsten heavy alloys. The microstructural parameters (grain size, connectivity, contiguity and solid volume fraction) were measured and were found to have a significant effect on the mechanical properties of tungsten-based heavy alloys. The result shows that the binding strength between the W and the matrix phase has a major influence on the ductility of tungsten-based alloys. The larger this binding force is, the better the ductility is.     

超声参振对Al-Fe合金凝固过程的影响

在Al-Fe合金的凝固过程中引入不同功率的超声振动,利用受控凝固和受控振动相结合的实验装置和方法,研究了超声参振对Al-Fe合金熔体温度场以及组织形态和抗拉强度的影响.实验表明:熔体的温度场随振动功率的增加和振动时间的延长而升高,并趋于一个平衡的温度场;超声参振可以显著细化先共晶FeAl3相,Al-Fe合金生长的组织形态的差异主要取决于凝固速度;超声参振凝固的Al-Fe合金的热稳定性好,有良好的应用前景.     

冷却介质对ZG30CrMn2Si2NiMo组织和力学性能的影响

研究了不同冷却介质对ZG30CrMn2Si2NiMo铸钢力学性能及组织的影响.试验结果表明,奥氏体化后空冷ZG30CrMn2Si2NiMo组织为板条贝氏体型铁素体和残余奥氏体组织,奥氏体化后淬火ZG30CrMn2Si2NiMo组织为板条马氏体、贝氏体型铁素体和残余奥氏体组织.ZG30CrMn2Si2NiMo获得板条马氏体、贝氏体型铁素体和残余奥氏体组织时,具有良好的力学性能.     

Cr3Si／Crl3Ni5Si2金属间化合物合金组织与高温滑动磨损性能的研究

利用水冷铜模激光熔炼炉制得了由初生枝晶Cr3Si和枝晶间Cr3Si／Crl3Ni5Si2共晶组成的金属间化合物合金。利用OM，SEM，TEM，EDS和XRD分析了该金属间化合物的显微组织，在400℃，500℃和600℃条件下测试了其耐磨性能。结果表明，由于Cr3Si和Crl3NisSi2硬度高、原子键合力强、组织细小、均匀，在高温滑动磨损条件下具有优良的耐磨性能。