NiCrAlYSi涂层/DD6单晶高温合金界面再结晶和互扩散行为

采用电子束物理气相沉积(EB-PVD)在单晶高温合金DD6基体上沉积NiCrAlYSi涂层.利用X射线衍射(XRD)、扫描电镜(SEM)、能谱仪(EDS)以及透射电镜(TEM)等研究了高温扩散过程中NiCrAlYSi/DD6的界面再结晶和互扩散行为.研究结果表明合金表面喷砂处理后的涂层试样经1 323 K真空热处理4 ...     

粉煤灰颗粒增强铝基复合材料的耐磨性研究

以粒度为80μm的粉煤灰为增强相,粒度为30μm的铝粉为基体,采用粉末冶金法成功制备了粉煤灰颗粒增强铝基复合材料。经SEM、金相显微镜等分析手段对制备的复合材料进行组织观察,并对其进行耐磨性测试。结果表明,粉煤灰含量为20%,烧结温度为650℃时,相对损率最小为0.1590%。随着粉煤灰含量和保压时间的增加,试样的耐磨性逐渐升高,随着烧结温度升高,试样的耐磨性呈现出先升高后降低的趋势。     

Single track and single layer formation in selective laser melting of niobium solid solution alloy

Selective laser melting (SLM) was employed to fabricate Nb-37Ti-13Cr-2Al-1Si (at%) alloy, using pre-alloyed powders prepared by plasma rotating electrode processing (PREP). A series of single tracks and single layers under different processing parameters was manufactured to evaluate the processing feasibility by SLM, including laser power, scanning speed, and hatch distance. Results showed that continuous single tracks could be fabricated using proper laser powers and scanning velocities. Both the width of a single track and its penetration depth into a substrate increased with an increase of the linear laser beam energy density (LED), i.e., an increase of the laser power and a decrease of the scanning speed. Nb, Ti, Si, Cr, and Al elements distributed heterogeneously over the melt pool in the form of swirl-like patterns. An excess of the hatch distance was not able to interconnect neighboring tracks. Under improper processing parameters, a balling phenomenon occurred, but could be eliminated with an increased LED. This work testified the SLM-processing feasibility of Nb-based alloy and promoted the application of SLM to the manufacture of niobium-based alloys.     

成分调整对DZ125合金凝固行为的影响

研究了标准成分的DZ125合金与以此为基础提高W、Al，降低Mo、Ti合金中的初生相的凝固顺序，确定了这两种合金在固-液范围内不同温度下的固-液相比例。结果表明，高W、Al低Mo、Ti合金显著缩小了合金凝固范围（Δ），使液相线温度提高了20℃，固相温度提高了70℃，并缩小失去技晶间毛细补缩能力时的温度与固相线之间的温度范围（ΔT2），从而减少了合金热裂倾向，提高了可铸性。Ti含量影响（γ＋γ'）共晶相尺寸、数量及形态，W、Wo对（γ＋γ'）共晶的数量、尺寸及形态均无影响。     

细晶铸造对K418合金拉伸性能的影响

测试了不同温度下细晶铸造和普通铸造Ｋ４１８合金的拉伸性能。结果表明，细晶铸造明显改善了合金的极限位伸强度和屈服强度，室温和６００℃的合金拉伸强度和晶粒平均直径符合Ｈａｌｌ－Ｐｅｔｃｈ关系。     

一种多晶石墨的拉伸蠕变行为

对一种多晶石墨材料进行了拉伸蠕变试验后,用ＲＡＭＡＮＯＲＵ１０００拉曼光谱仪对蠕变前后的试样作了分析,并用扫描电镜观察了蠕变前后试样纵向剖面的孔隙变化。结果表明：在１７００℃,０．７ＭＰａ的应力作用下多晶石墨材料不发生明显蠕变。蠕变初期可用ε－ε０＝Ａｔｎ进行描述,在不同温度和应力下ｎ值从０．４８５～０．８之间变化。在同一应力条件下,随温度提高,ｎ值增大。激光拉曼光谱仪和扫描电镜分析表明,多晶石墨蠕变后石墨化程度增加、孔隙增多、变大。     

粉末GH4169 合金中的原始颗粒边界问题

探讨了粉末GH4169高温合金中的原始颗粒边界的形成机理、其对合金组织性能的影响以及消除措施等。结果表明:粉末GH4169合金中原始颗粒边界组织主要由MC碳化物构成,而在粉末成型前进行预热处理可以有效抑制原始颗粒边界组织的生成,提高合金综合性能。     

Grinding force and surface quality in creep feed profile grinding of turbine blade root of nickel-based superalloy with microcrystalline alumina abrasive wheels

Creep feed profile grinding of the fir-tree blade root forms of single crystal nickel-based superalloy was conducted using microcrystalline alumina abrasive wheels in the present study. The grinding force and the surface quality in terms of surface topography, subsurface microstructure, microhardness and residual stress obtained under different grinding conditions were evaluated comparatively. Experimental results indicated that the grinding force was influenced significantly by the competing predominance between the grinding parameters and the cross-sectional root workpiece profile. In addition, the root workpiece surface, including the root peak and valley regions, was produced with the large difference in surface quality due to the nonuniform grinding loads along the root workpiece profile in normal section. Detailed results showed that the surface roughness, subsurface plastic deformation and work hardening level of the root valley region were higher by up to 25%, 20% and 7% in average than those obtained in the root peak region, respectively, in the current investigation. Finally, the superior parameters were recommended in the creep feed profile grinding of the fir-tree blade root forms. This study is helpful to provide industry guidance to optimize the machining process for the high-valued parts with complicated profiles.     

基于应力循环特征的裂纹萌生寿命预测方法

以两种镍基高温合金的应力循环特征为基础,即粉末高温合金FGH95的循环硬化继而软化及变形高温合金GH4169的循环软化特性,寻求载荷历程相关的损伤参量,进而建立应力弱化损伤模型,以考虑载荷历程对疲劳寿命的影响.建立的应力弱化损伤模型可以较好地预测不同循环载荷条件下的疲劳寿命,其预测精度不低于传统方法,且优势在于使建立模型所需要的试样数量大大减少.      

Ru过渡层对NiCoCrAlY涂层与DD6单晶高温合金界面扩散行为的影响

针对第二代单晶高温合金DD6开展了一种具有阻扩散功能的金属防护涂层的探索性研究.采用电镀和电子束物理气相沉积(EB-PVD)方法在DD6单晶高温合金上制备了NiCoCrAlY/Ru双层结构涂层,同时采用EB-PVD在单晶合金上沉积了单层NiCoCrAlY涂层.研究结果表明,在1 050℃大气环境中扩散处理300 h后,...