乙炔气体流量对纳米TiC类金刚石复合膜的化学结构及力学性能影响

采用离子注入与反应磁控溅射相结合的方法在钛合金及硅片基体表面上制备了纳米TiC类金刚石(DLC)复合膜.通过纳米压痕技术检测了薄膜的纳米硬度，显微划痕试验评估了薄膜的结合力.通过X射线光电子能谱及X射线衍射表征了薄膜的化学结构.结果表明，通过改变C₂H₂气体流量，可以达到控制薄膜中钛原子含量的目的，合适的C₂H₂气体流量可以在DLC膜中形成较多的纳米TiC晶粒，形成DLC包覆TiC晶粒的复合结构，使DLC膜力学性能得到明显提高.另外，划痕试验表明掺钛、先注入后沉积工艺都使薄膜的结合力得到了较大提高. 关键词： 纳米TiC类金刚石复合膜 类金刚石膜 力学性能     

Characterization of laser‐treated Rene 41 surface due to B4C and SiC particles at surface prior to laser treatment

Laser surface treatment of Rene 41 high‐performance alloy is carried out with the presence of hard particles at the surface. B₄C and SiC particles are uniformly distributed within 40 µm carbon film at the workpiece surface prior to laser treatment process. The effect of hard particles on residual stress and microhardness variations is investigated at the treated surface. Morphological and metallurgical changes in the treated layer are examined by using electron microscopy, energy dispersive spectroscopy, and X‐ray diffraction. Residual stress formed at the surface is determined from the X‐ray data. It is found that the treated surface is free from asperities such as large size voids and cracks. A dense layer is formed in the surface region, which causes volume shrinkage while contributing to microhardness and residual stress enhancement at the surface. B₄C hard particles result in the highest residual stress and microhardness at the surface, which is attributed to its high thermal expansion coefficient. Copyright © 2013 John Wiley & Sons, Ltd.     

TiC、TiC1-x、(Ti1-xNbx)C电子结构的计算

采用离散变分x_α法（DV-X_α法）对TiC理想晶体、空位和掺杂缺陷结构中的电子结构进行了计算．通过选取分子簇模型,模拟了理想晶体、空位和掺杂缺陷情况．采用多重散射离散变分X_α法,通过自治迭代来求解局域密度泛函方程,得到了各个分子簇模型的电子结构．分析计算结果发现,在理想TiC结构的态密度图中,费米能级位于两峰之间．但在费米能级处的电子态密度不为零,这提供了TiC导电性的来源．在空位模型中,发现电子态密度在费米能级处有较大的值,说明空位的存在有利于提高TiC的导电能力．对于Nb掺杂后的电子结构,在费米能级处存在一个电子态密度峰,因而也有利于提高其导电性．在计算的过程中考虑到了分子簇模型边界条件带来的电行转移效应对电子结构的影响,通过提供适当的环境势,得到了较精确的计算结果．与已有的计算结果进行了对比,有较好的一致性．     

Effect of Ti and C additions on structural and magnetic properties of (Pr,Nd)–Fe–B nanocrystalline magnetic materials

Effects of titanium carbide (TiC) addition on structural and magnetic properties of isotropic (Pr,Nd)–Fe-B nanocrystalline magnetic materials have been investigated. In this work, we investigate the effect of TiC addition on a (Pr,Nd)-poor and B-rich composition, as well as on a B-poor and (Nd,Pr)-rich composition. Rapidly solidified (Pr,Nd)–Fe–B alloys were prepared by melt-spinning. The compositions studied were (Pr_1−xNd_x)₄Fe₇₈B₁₈ (x=0, 0.5, and 1) with addition of 3 at% TiC. Unlike the (Pr_xNd_1−x)_9.5Fe_84.5B₆ materials that present excellent values for coercive field and energy product, the (Pr,Nd)-poor and B-rich composition alloys with TiC addition present lower values. Rietveld analysis of X-ray data and Mössbauer spectroscopy revealed that samples are predominantly composed of Fe₃B and -Fe. For the RE-rich compositions (Pr_xNd_1−x)_9.5Fe_84.5B₆ (x=0.1, 0.25, 0.5, 0.75, and 1) with the addition of 3 at% TiC, the highest coercive field and energy product (8.4 kOe and 14.4 MGOe, respectively) were obtained for the composition Pr_9.5Fe_84.5B₆.     

合金元素对TiC/奥氏体界面稳定性影响的第一性原理计算

界面结合强度与材料的强度、硬度、耐磨损、耐腐蚀等性能息息相关,TiC是钢中常见的析出相,研究它与铁基体的界面结合状态,探寻合理的界面强度提升方案,对提升钢的性能具有十分重要的理论意义和应用价值.本文以TiC/奥氏体基体界面为研究对象,采用基于密度泛函理论的第一性原理计算方法从原子尺度上研究TiC/奥氏体基体界面的结合状态.首先本文对界面结合强度以及电子结构进行了计算分析,之后进行高通量计算,研究过渡族金属元素(Mn、Tc、Re、Ru、Os、Co、Rh和Ir)在TiC/奥氏体基体界面的偏析行为及其对界面结合强度的影响,最后通过差分电荷密度分析并解释过渡族金属元素的作用机理.计算研究表明,掺杂Re元素可显著提升界面的强度,为实验上设计高性能钢铁材料提供了新的思路.     

Cr12模具钢表面真空烧结Ni60-TiC涂层的摩擦磨损性能

本文采用热压烧结方法在Cr12模具钢表面制备Ni60-TiC涂层,按照TiC的比例含量分别为0;、15;、25;以及35;,制备出4种配比的试样.采用维氏硬度计进行了显微硬度测试,采用摩擦磨损实验并结合SEM及EDS对Ni60-TiC涂层试样观测和分析,得出TiC加入量对涂层硬度以及摩擦性能的影响.结果表明:涂层中加入适量的TiC有助于提高涂层硬度以及摩擦性能,且涂层中TiC含量为25;时效果最为显著.     

感应熔覆原位合成TiC增强金属基复合涂层组织与抗磨性能的研究

以Ni60A、Ti粉和石墨粉为原料,利用感应熔覆技术在16Mn钢基材表面制备出原位自生TiC颗粒增强金属基复合涂层,分析了涂层的显微组织,在常温干滑动摩擦条件下评价了涂层的耐磨性能.结果表明:复合涂层由TiC颗粒、γ-Ni奥氏体枝晶和枝晶间M23C6共晶组织组成;随着载荷增加,感应熔覆涂层磨损质量损失缓慢增大,16Mn钢磨损质量损失迅速增大,熔覆涂层具有优异的抗磨性能,其磨损机制主要为擦伤式磨损.     

CeO2对原位TiC弥散强化钢组织和性能的影响

以CeO2为活性添加剂,用原位接触法和铸造工艺方法制备了TiC弥散强化钢。实验表明：添加0.2%（质量分数）CeO2,可使TiC弥散强化钢中的TiC颗粒分布更加弥散,且有细化TiC颗粒的作用;从而提高了强化钢的强度和塑性,并在一定程度上改善钢的耐磨性能。然而,添加过量的CeO2却使TiC弥散强化钢显微组织中的TiC出现团聚。     

TiC晶须的形貌

用气相催化无衬底化学气相沉积法制备TiC高温陶瓷晶须。经X射线物相分析、电子衍射测定和扫描电镜观测。分析了TiC晶须的形貌。     

TiC／NiCr金属陶瓷复合材料摩擦磨损性能

用粉末冶金法制备不同ＴｉＣ颗粒含量的ＴｉＣ／ＮｉＣｒ金属陶瓷复合材料,讨论了它们的显微组织特点,研究了该复合材料在水润滑条件下的摩擦磨损性能,试验结果表明：随着ＴｉＣ颗粒含量增加,金属陶瓷的耐磨性能明显提高,在本试验条件下,当ＴｉＣ颗粒体积分数为６７％左右时,ＴｉＣ／ＮｉＣｒ金属陶瓷复合材料的耐磨性能最佳;其磨损失效机制主要是在磨损过程中ＴｉＣ颗粒以显微脆断方式剥落产生磨损,磨损表面呈现微切削及显