Metal injection molding of W-Cu powders prepared by low energy ball milling

Low energy ball milled W/Cu powders were used for metal injection molding (MIM) in order to overcome the low powder volume fraction of MIM parts after debinding as well as the inherently poor sinterability of the W-Cu powder compacts. Ball milling was carried out using commercial fine W and Cu powders to form a powder mixture suitable for injection molding. W powders showed no change in either size or shape during the milling process, but the ductile Cu powders were easily deformed to a three-dimensional equiaxed shape, having a particle size comparable to that of W powders. This modification of powder characteristics by ball milling resulted in an improvement of the solid loading of roughly 58%, maintaining a high and uniform powder packing density in the feedstock. The densification behavior of W-Cu MIM parts is also discussed on the basis of the relationship between Cu composition and W particle size.     

Cu含量对纳米晶W-Cu复合粉末烧结行为的影响

研究了Cu含量对机械合金化纳米晶W—xCu(X=15,20,25)复合粉末烧结行为的影响,并考察了一种新型晶粒长大抑制剂对抑制W晶粒长大的作用,探讨了其作用机理。结果表明,Cu含量增加有利于烧结致密化,并减弱聚晶长大的趋势。纳米晶W—Cu粉末在1200-1250℃烧结30min后,致密度为97％～98％,对应的晶粒度约为300～500nm,其中1200℃烧结30min对应的晶粒尺寸约为300～350nm,明显低于国外1μm的晶粒度水平,新型晶粒长大抑制剂有望对W晶粒长大有明显的抑制效果。     

冷压成型方向对W-Cu电触头材料性能的影响

针对轴向、径向两种压制方向成型的W—Cu合金,采用烧结熔渗法制备W—Cu／Cu整体电触头材料,测定结合面的抗拉强度及W—Cu合金的电性能、显微组织和抗弯强度。结果表明,轴向压制产品烧结后的结合强度远大于径向压制产品烧结后的结合强度。W—Cu合金的物理性能也是轴向压制的比径向压制的好,但两种压制方法对材料的抗弯强度影响不大。     

钨粉粒度对电极用钨铜合金组织和性能的影响

钨粉粒度是影响钨铜合金组织和性能的主要因素之一,采用不同粒度(2.65 μm、4 μm、8 μm)的钨粉用熔渗法制备钨铜合金,通过性能检测和组织分析研究了钨粉粒度对该合金密度、硬度和电导率的影响.实验结果表明:钨粉粒度越细,钨铜合金的密度和硬度越大;但是由细钨粉制备的W-Cu合金闭孔较多,均匀性较差,电导率较小.钨粉粒度为4μm时所得产品综合性能最好,W-30Cu合金密度为14.44 g/cm3、硬度为HB 212、电导率为24.2 MS/m.W-20Cu合金密度为15.38 g/cm3,硬度为HB225,电导率为22.6 MS/m.     

钨铜合金的最新研究进展及其应用

综述了近年来国内外钨铜合金材料制备技术方面的主要进展，并介绍了最新研制成功的几种新型钨铜合金材料，如梯度钨铜材料、纳米钨铜材料等，以及钨铜合金在民用和军事工业上的主要应用，并简要地探讨了钨铜合金今后发展的主要动向和研究重点。     

W-Cu(Mo-Cu)复合材料的研究进展

W-Cu或Mo-Cu两相复合材料具有较高的导热性和较低的热膨胀系数,在大功率器件中被视为一种很好的热沉材料。近年来,有关W-Cu或Mo-Cu作为电子热沉材料的研究在国内外已有一些报道。作者主要就近几年钨铜复合材料研究的几个主要热点问题进行综述报道。分析认为,梯度结构功能材料、纳米结构材料以及注射成形工艺在钨铜复合材料领域中的应用是当今钨铜电子材料发展的主要方向,同时对国内外最新研究进行了归纳总结,指出了今后发展的主要动向。     

CuW复合材料的超声波探伤研究(二)

本文承接第一部分，主要研究了在实际超声波检测过程中如何采用对比试块通过多次反射波法和垂直扫查法对材料进行评价的方法。结合检测实际，给出了实际检测的操作方法和评价方法以及相应的参考标准波形和典型的缺陷图形。     

Copper Alloys From Metal Oxide Precursors for High Conductivity Applications

Extrusion of oxide powders allows fabrication of thin-walled metal articles to produce controlled-geometry, low-density copper alloy architectures. Shapes formed with copper oxide powders mixed with alloying oxides are reduced and sintered to produce high relative densities in the thin walls. This technology has produced square-cell honeycomb extrusions, which are being characterized for heat sink applications. This effort is to determine the bulk properties of alloys produced by this type of thermo-chemical powder processing and to explain behavior based on the final chemistry and microstructure of the alloys. Compositions investigated include Cu, Cu-Ni, Cu-Ag, W-Cu, Cu-Invar, Cu-Al₂O₃, and Cu-Cr alloys. Alloys have been characterized for relative density, thermal conductivity, and grain size. Mechanical properties including tensile and yield strength and elongation were measured on Cu-Ni and Cu-Ag, and the results were analyzed based on porosity and composition of the alloys. Properties were compared to alloys made through conventional processing and powder metallurgy.     

细晶钨铜复合材料制备工艺的研究

将W-20％Cu混合粉末在行星式高能球磨机中机械合金化(MA)。经过一定时问球磨后可以得到W晶块尺寸30nm左右的纳米粉末。测定了粉末晶粒尺寸、粉末的粒度、比表面、松装密度和振实密度等性能。粉末的晶块尺寸用XRD分析得出。研究了MA W-2096Cu粉末烧结后的显微组织。研究表明，球磨后粉末在1200～1300℃下烧结即可达到近全致密，相对密度在99．596以上，拉伸强度达到780MPa以上，伸长率大于3．5％，钨晶粒尺寸在1～2μm左右。     

W-Cu薄膜沉积初期亚稳态固溶体形成机制

采用直流双靶磁控溅射共沉积的方法制备了W含量为75%(原子分数)的W-Cu薄膜,并通过EDS、XRD、SEM、TEM等对W-Cu薄膜沉积初期的微观形貌及组织结构进行了表征和分析。结果表明,沉积初期,随着沉积时间延长,W-Cu薄膜有逐渐晶化的趋势,并形成了W(Cu)基亚稳态固溶体,且Cu在W中的固溶度逐渐增加。沉积10s时薄膜呈长程无序、短程有序的非晶态,局部有由于靶材粒子扩散不充分而形成的小于5nm的W、Cu纳米晶;20s时局部纳米晶消失但晶化程度升高;30s时晶化显著。沉积初期W-Cu薄膜随沉积时间延长逐渐晶化的原因是沉积过程中高能量的原子或原子团与已沉积的原子碰撞,传递能量,促进原子进一步扩散,克服了薄膜的晶化形成能,从而形成了亚稳态的W(Cu)固溶体。