镁合金AZ91HP强流脉冲电子束表面处理及抗蚀性能研究

研究了强流脉冲电子束表面处理对镁合金AZ91HP腐蚀性能的影响。通过动电位极化曲线测定，处理样品在5％NaCl溶液中的抗蚀性能有显著改善。72h盐浸失重法测试中，处理样品的腐蚀速度最大可以降低一个数量级。扫描电镜(SEM)及电子探针(EPMA)分析发现，强流脉冲电子束轰击处理在AZ91HP样品表层引发快速熔凝过程，进而导致镁、铝元素的含量及分布形式发生变化。样品表面重熔层中Al元素的过饱和固溶及成分均匀化是改善其腐蚀性能的主要原因。     

Effect of high current pulsed electron beam treatment on surface microstructure and wear and corrosion resistance of an AZ91HP magnesium alloy

This paper reports an analysis of the microstructure and property modifications on a commercial Mg alloy AZ91HP treated by using High Current Pulsed Electron Beam (HCPEB). It is shown that, a thin layer consisting of nanograined MgO formed on the top surface after HCPEB (electron energy ∼ 30 keV, pulse duration 1 μs, energy density ∼ 3 J/cm²) treatment, below which is a melted layer with depth of about 8-10 μm. The heat affected zone (HAZ) underneath the melted layer and stress wave affected zone contains many stress induced deformation marks. Meantime, a nearly complete dissolution of the intermetallic phase Mg₁₇Al₁₂ in the melted layer is observed, leading to the formation of a super-saturated solid solution on the surface. This is due to the solute trapping effect occurred during the fast solidification process. As a result, the wear and corrosion resistance of the alloy were significantly improved as shown by sliding friction, wear and immersion tests.     

Improvement of Wear Resistance of Magnesium Alloy AZ91HP by High Current Pulsed Electron Beam Treatment

MAGNESIUM ALLOYS exhibit high strength toweight ratio and stiffness and are finding theirapplications in air,automobile and electronic industries.Despite the worldwide growing interests inmagnesium alloys,their inferior wear resistance is aserious impediment.Considering that wear is asurface-related behavior,surface modification canresolve the problem.Recently,intense and pulsed energetic beams areemerging as new and effective methods for surfacemodification.The High Current Pulsed Ele…     

316L不锈钢强流脉冲电子束表面钛合金化及其耐蚀性

利用强流脉冲电子束对不锈钢表面进行了快速钛合金化。将精细钛粉预涂在基体表面后采用强流脉冲电子束对其进行后处理。在电子束对表面的快速加热熔化、混合及增强扩散效应的作用下,部分钛熔入基体表层形成一层富钛层。由于钛的添加有利于形成α相,合金层由α相和γ相混合组成。在模拟体液中的动态极化测试表明,316L医用不锈钢经强流脉冲电子束表面钛合金化后,其在模拟体液中的耐腐蚀性能获得了显著的提高。     

回火对强流脉冲电子束辐照M50钢重熔层耐蚀性能的影响

利用强流脉冲电子束技术对M50钢进行了辐照处理,并对重熔层在550、600和675 ℃条件下进行了回火处理。采用XRD、SEM和电化学综合测试系统等手段分析了不同处理方式对重熔层组织和耐蚀性能的影响。结果表明,M50钢经过强流脉冲电子束辐照后表层的碳化物溶解,马氏体转变被抑制,耐腐蚀性能上升。经过回火处理后,重熔层内残留奥氏体分解,耐蚀性能逐渐降低。     

强流脉冲电子束对TC4钛合金表面形貌的影响

采用强流脉冲电子束对TC4钛合金表面进行处理,研究了电子束处理后TC4钛合金的表面形貌、表面粗糙度变化。结果表明,电子束处理对表面粗糙度的影响与预处理试样表面状态有关:当预处理试样表面粗糙度大于0.031μm时,电子束处理后其粗糙度降低,在该条件下表面层的缺陷较多,表面熔化占主导作用;当预处理试样表面粗糙度为0.031μm时,电子束处理后粗糙度增大,此时表面熔坑形成占主导作用。因此电子束处理有增加或减小粗糙度的双重特性,这取决于表面熔化和熔坑形成两种机制的强弱状态。当预处理试样的粗糙度大于0.468μm时,由于电子束处理过程中的热力耦合过程,处理后表层极易形成裂纹。     

强流脉冲电子束辐照YG8硬质合金的组织与性能

采用强流脉冲电子束(HCPEB)表面改性技术对YG8硬质合金表面进行辐照处理试验。利用金相显微镜、X射线衍射仪和扫描电镜对处理样品的表层组织进行分析,测量改性样品的显微硬度和摩擦磨损性能指标。结果表明,强流脉冲电子束处理使YG8样品表层重熔平整,WC颗粒形状圆整并与粘结剂Co基体发生溶解扩散,表层显微硬度增加到3523.6 HK,耐磨性提高约19%。     

强流脉冲离子束辐照AZ31镁合金的干滑动磨损行为

用脉冲宽度为70~80 ns,束流密度为200 A/cm2,辐照次数为1、5和10次的强流脉冲离子束(HIPIB)辐照AZ31镁合金,用扫描电子显微镜(SEM)、光学显微镜(OM)以及干滑动磨损试验对辐照后试样进行表征和干滑动磨损行为研究。结果表明,HIPIB辐照试样获得了显著优于未辐照试样的耐磨性能,且随着辐照次数的增加改善作用增强。具有最高硬度的10次辐照试样的磨损率较未辐照试样减小约一个数量级,磨粒磨损倾向大大降低,HIPIB辐照使得镁合金的磨损机制从单一的磨粒磨损转变为磨粒磨损和氧化磨损的混合磨损,这主要归结于辐照表面改性层晶粒的细化而导致镁合金表面硬度的提高。     

Surface modification of Al-Pb alloy by high current pulsed electron beam

Al-Pb alloy was modified by high current pulsed electron beam and the microstructure, hardness and tribological characteristics were characterized by scanning electron microscopy, electronic microanalysis probe microanalysis, Knoop hardness indentation and pin-on-disc type wear testing machine. The results show that the microstructure and hardness can be greatly improved, and the modification layer consists of a molten zone, an overlapped zone of heat-affected and quasistatic thermal stress-affected zone and a transition zone followed by the substrate. The tribological properties of high current pulsed electron beam irradiated Al-Pb alloy are correspondingly improved largely. Optical observation and scanning electron microscopy analysis reveal that the low wear rate and lowest level in coefficient of friction at high load level for irradiated Al-Pb alloy are due to the formation of a lubricious tribolayer covering the worn surface, which is a mixture of Al2O3, Pb3O4 and silicate. The wear mode varies from oxidative wear at low load to film spalling at high load and, finally, adhesive wear.     

HCPEB作用下镀铝CoCrAlY涂层的表面微观结构状态

采用大气等离子喷涂在GH4169镍基高温合金表面沉积CoCrAlY涂层,利用电子束蒸发镀膜技术在涂层表面沉积纳米铝膜,分别对镀铝前后的涂层使用强流脉冲电子束进行辐照处理,对处理前后的涂层表面进行成分及结构分析.XRD结果显示,经过HCPEB轰击之后,涂层表面纳米铝膜重熔,钴类氧化物消失,新增铝相,且随着轰击次数增加,β-CoAl含量增加.结构分析表明,电子束轰击可以使原始涂层表面尖角、孔洞、夹杂等消失,形成非常致密的凸起胞状体纳米超细晶结构,有利于抑制腐蚀性气体的侵入,同时铝含量的增加有利于抗氧化性能的提高.     

Numerical simulation of thermal-mechanical process of Al-Si-Pb alloy treated by high current pulsed electron beam

The modified microstructure of AI-Si-Pb alloys irradiated by high current electron beam （HCPEB） reveals three distinct regions： a molten zone, an overlapped zone of heat-affected and quasistatic thermal stress-affected zone, and a transition zone followed by the substrate. The hardness and wear properties of the alloys were significantly improved. To better understand these changes in microstructure and properties, the physical model for the simulation of temperature and quasistatic stress fields was established. Based on experimental investigation and physical models, the temperature field and stress field were simulated for Al-Si-Pb alloy. The starting melting position, largest crater depth, melting layer thickness, and quasistatic stress distribution were obtained. These results reveal the mechanism of crater formation on the surface and improvement of hardness and wear resistance.     

Improved Corrosion Resistance of Magnesium Alloys AZ31 and AZ91HP by High Current Pulsed Electron Beam Treatment

MAGNESIUM ALLOYS are now receiving more andmore applications in the electronic communication,aeronautic and automotive products due to their lowdensity,high strength to weight ratio and goodcastability[1-3]-However,the inherently poorcorrosion resistance of magnesium alloys limits theirfurther utilization.Therefore,significant efforts havebeing made to find one way that allows improving thecorrosion resistance of magnesium alloys effectively.Increasing the purity of magnesium alloy and t…     

强流脉冲电子束表面改性AZ31镁合金的耐磨耐蚀性能

选用强流脉冲电子束对AZ31镁合金进行表面改性处理,分析了改性后的AZ31镁合金表面显微结构,测量处理前后AZ31镁合金的耐磨性能和耐蚀性能。结果表明,脉冲电子束处理后AZ31合金表面出现了典型的熔坑形貌,同时熔坑周围有应力波作用产生的褶痕。由电子束快速凝固作用所产生的表层晶粒细化和固溶强化显著提高了AZ31合金的耐磨性。此外,电子束表面改性导致表层镁、铝元素含量及分布形式发生变化。样品表层铝元素的升高是改善其腐蚀性能的主要原因。     

AZ91HP镁合金电沉积Ni-SiO_2纳米复合镀层的显微结构与耐磨性(英文)

以AZ91HP镁合金为研究对象,以纳米氧化硅为第二相粒子,通过纳米复合电沉积法制备AZ91HP镁合金Ni-SiO2纳米复合镀层。利用扫描电镜观察纳米复合镀层的显微形貌与微观结构,利用显微硬度计测定纳米复合镀层显微硬度,利用M200摩擦磨损试验机测试纳米复合镀层的耐磨性能。结果表明:在AZ91HP镁合金表面获得了结晶均匀、结构致密的Ni-SiO2纳米复合镀层;纳米复合镀层剖面形貌显示纳米复合镀层与镁合金基体结合良好;镀液中纳米颗粒含量为10g/L时,AZ91HP镁合金表面电沉积Ni-SiO2纳米复合镀层的显微硬度最高,最高达HV367;摩擦磨损试验表明纳米复合镀层与镀镍层、镁合金基体相比,耐磨性明显提高,这是由于纳米颗粒的细晶强化和弥散强化所致;纳米复合镀层的磨损机制主要是磨粒磨损,镁合金基体磨损机制为粘着磨损,镀镍层磨损机制为剥层磨损。     

强流脉冲离子束辐照镁合金微弧氧化膜的耐腐蚀性能

采用强流脉冲离子束在束流密度为200 A/cm2、辐照次数为1~10次条件下对AZ31镁合金微弧氧化膜进行辐照改性处理。采用扫描电子显微镜对氧化膜的表面及截面形貌进行表征;在Princeton Applied Research(PAR)2273型电化学工作站测量氧化膜的极化曲线。结果表明:在束流密度200 A/cm2、5次辐照条件下氧化膜表面获得连续、致密的改性层;以3.5%NaCl溶液为腐蚀液,氧化膜表面发生的腐蚀过程由辐照前的活化溶解向辐照后的钝化-孔蚀击穿转变;在束流密度200 A/cm2、5次辐照条件下击穿电位提高到最大值-800 mV(vs SCE)。强流脉冲离子束辐照产生的连续致密改性层是氧化膜耐蚀性改善的主要原因。     

回火对Cr4Mo4V钢电子束Cr合金化层组织和性能的影响

研究了Cr4Mo4V钢电子束Cr合金化层结构随回火温度及时间变化的演化规律。采用XRD和TEM研究了Cr合金化层在回火过程中的物相变化,采用纳米硬度计和电化学工作站分别测试了Cr合金化层硬度和耐蚀性随回火温度的变化。结果表明,回火过程中纳米级碳化物从合金化层中析出,使合金化层硬度增加,随着回火时间和温度的增加,碳化物发生长大,硬度随之降低。碳化物的析出会导致基体Cr元素的下降,耐蚀性降低,但仍优于原始Cr4Mo4V钢。     

强流脉冲离子束辐照挤压态AZ31镁合金性能

利用强流脉冲离子束(C+、H+)对变形镁合金AZ31的挤压态靶材分别进行0、1、30和50次辐照试验,分析辐照前后物相组成,检测随辐照次数增加靶材表面的显微硬度,并通过阳极氧化和盐雾试验检测耐蚀性能。结果表明,随HIPIB辐照次数增加,靶材表面显微硬度呈提高趋势,50次辐照表面显微硬度270 HV0.01,较原始靶材的63.7 HV0.01提高了3倍多;极化曲线显示自腐蚀电位和击穿电位提高,自腐蚀电流减小,30次辐照的自腐蚀电位达到-1363 mV,钝化区间为1065 mV;辐照处理后在盐雾试验中形成钝化膜使靶材腐蚀速率显著降低了65%,耐蚀性能得到较大改善。     

Corrosion Resistance of AZ91 Mg Alloy Modified by High-Current Pulsed Electron Beam

The high-current pulsed electron beam(HCPEB) treatment with current density 6 J/cm~2 was applied on AZ91 Mg alloy to improve its corrosion resistance. Results showed that the net-like Mg_(17)Al_(12) disappeared on the surface of AZ91 Mg alloy after irradiation by HCPEB, which was instead of supersaturated Al element on the surface. Nevertheless, the application of HCPEB also led to the formation of crater-like and groove-like structures as well as micro-cracks on the surface of AZ91 Mg alloy. After HCPEB treatment by 3, 5 and 10 pulses, the AZ91 Mg alloy exhibited better corrosion resistance.However, the increasing amount of micro-cracks reduced the anti-corrosive properties of AZ91 Mg alloy as the pulse increased to 20 and 30.     

Surface treatment of 0.20% C carbon steel by high-current pulsed electron beam

A high-current pulsed electron beam（HCPEB） generated on the system of Nadezhda-2 was applied to improve the microstructure and performance of 0.20% C low carbon steel. Surface layers of the samples bombarded by explosive electron beam at different pulses was observed by using electron microscopy. The physical model of the thermal-stress process and related modification mechanism as a result of HCPEB irradiation was also investigated. After HCPEB post treatments, obvious changes in microstructure and significant hardening occur in the depth of 200-250 μm from the surface after HCPEB irradiation. Rapid heating and subsequent rapid solidification induce heavy plastic deformation, which results in that the laminated structure of pearlite is substituted by dispersive rounded-like cementites in the near-surface. The effect of HCPEB treatment can reach more than 500 m depth from the surface. The original crystalline structure is changed to a different degree that grows with the numbers of bombardment, and in the surface layer amorphous states and nanocrystaline structures consisting of grains of γ-phase and cementite are found. The violent stress induced by HCPEB irradiation is the origin of the nanostructured and amorphous structure formation.