超声表面滚压处理对AZ31B镁合金组织和性能的影响

目的 研究AZ31B镁合金在超声表面滚压处理后,表面微观结构、显微硬度和表面粗糙度的变化及其在拉伸试验过程中对AZ31B镁合金内部组织的影响.方法 利用超声表面滚压处理在AZ31B镁合金表面制备梯度变形层.利用X射线衍射仪、EBSD、显微硬度仪和表面粗糙度仪,分析试样表面的微观结构、显微硬度和表面粗糙度.对超声表面滚压...     

激光冲击处理对AZ31B镁合金表面质量的影响

为了研究激光冲击处理对AZ31B镁合金表面质量的影响,采用波长1 064 nm、脉冲宽度15 ns、脉冲能量10J、光斑直径3 mm的钕玻璃脉冲激光器,对轧制态AZ31B镁合金薄板试样表面进行激光冲击处理.试验结果表明:单次冲击所形成的凹坑深度达到39.122 μm;由于激光能量分布不均匀,导致AZ31B镁合金表面粗糙度值增大.     

AZ91镁合金耐腐蚀性能的研究进展

AZ91是工业上应用最为广泛的镁合金之一,但其较差的耐腐蚀性能阻碍了其进一步的推广应用.分析了AZ91合金腐蚀速率大小的几个主要影响因素,介绍了改善AZ91镁合金耐蚀性能的方法.     

AZ91镁合金微弧氧化处理研究

研究了AZ91镁合金的微弧氧化处理,结果表明,在不同处理时间AZ91镁合金表面分别形成了厚度为28～106 μm的陶瓷膜层.膜层分外层膜和内层膜两层,内层膜质地较为致密;外层膜质地较为疏松.疏松层主要成分为Mg2SiO4 和 MgSiO3,致密层主要成分为MgO.     

AZ31镁合金表面处理工艺对其改性结果的影响对比

针对AZ31镁合金应用过程中对表面摩擦磨损性能、耐腐蚀性能有特殊要求的状况,分析了AZ31镁合金可能的表面改性技术,比较了不同改性方法的具体实现途径,并提出了加强复合改性技术研究的重要意义。     

退火处理对AZ31B镁合金板材组织与性能的影响

沿板材不同挤出方向截取试样,研究了不同退火工艺条件下AZ31B镁合金板材的组织和力学性能.结果表明,AZ31B镁合金挤压态板材相组成以α-Mg为主,带有部分Al2Mg相.由于挤压变形使板材形成了平行于板平面的(0001)基面织构,造成板材的力学性能各向异性,其中以板材挤出方向呈90°的试样综合力学性能最高,其抗拉强度为274.3 N/mm2,伸长率为14.5%.退火处理过程中形成的再结晶组织,使晶粒得到细化,改善了材料的力学性能,其中以取样角度为0°的试样力学性能改善最为显著.此外,退火处理能使板材的断裂特征由供应态的脆、韧性混合断裂向韧性断裂转变.     

植酸转换膜对AZ31镁合金电化学腐蚀性能的影响

镁合金的耐腐蚀性能不理想,从而严重阻碍了镁合金大规模的商业应用。在商用AZ31镁合金表面制备了植酸转换膜,采用扫描电镜、能谱仪、电化学工作站等进行了合金电化学腐蚀性能的检测。结果表明,表面制备的植酸转换膜显著改善了商用AZ31镁合金的电化学腐蚀性能;与未经表面处理的商用AZ31镁合金相比,制备了植酸转换膜的AZ31镁合金在20℃电解液中的开路电位和腐蚀电位分别正移185 m V、238 m V;在质量分数为5%的KOH电解液中的开路电位和腐蚀电位分别正移221 m V、218 m V。     

退火处理对AZ31B镁合金板材组织与性能的影响

沿板材不同挤出方向截取试样,研究了不同退火工艺条件下AZ31B板材的组织和力学性能。结果表明,挤压态板材相组成以α-Mg为主,带有部分Al2Mg相。由于挤压变形使板材形成了平行于板平面的(0001)基面织构,造成板材的力学性能各向异性,其中以板材挤出方向呈90°的试样综合力学性能最高,其抗拉强度为274.3MPa,伸长率为14.5%。退火处理过程中形成的再结晶组织,使晶粒得到细化,改善了材料的力学性能,其中以取样角度为0°的试样力学性能改善最为显著。此外,退火处理能使板材的断裂特征由供应态的脆、韧性混合断裂向韧性断裂转变。     

电解等离子体过程中电解液对AZ31B镁合金力学性能的影响(英文)

以NaOH+Na2SiO3为基础电解液,分别加入Na2SiF6或NaF制备镁合金涂层。将AZ31B镁合金基体在200 V交流和260 V直流的混合电压下等离子体电解处理30 min。通过XRD和SEM方法分析陶瓷涂层的结构和形态。利用销盘式磨损实验和维氏硬度实验研究涂层的耐磨性和硬度。在Na2SiF6和NaF电解液中形成的涂层主要成分是MgO和Mg2SiO4。在Na2SiF6电解液中制备的涂层的显微硬度为HV1100,而在NaF电解液中制备的涂层的显微硬度约为HV900。结果表明:AZ31B镁合金的力学性能可以通过选择适当的电解液得到增强。     

AZ31B镁合金及其焊接接头的疲劳断裂机理

对AZ31B镁合金进行疲劳实验,在2×106循环次数下,母材、对接接头、横向十字接头和侧面连接接头的疲劳强度分别为66.72,39.00,24.38和24.40MPa。采用光学显微镜对裂纹扩展特征进行分析,结果表明,AZ31B母材的疲劳裂纹宏观扩展路径平滑,但微观观察发现疲劳裂纹扩展方向曲弯,有些裂纹分成两岔;裂纹尖端扩展均为沿晶扩展。焊接接头裂纹均在焊趾部位起裂,对接接头和横线十字接头的裂纹沿着热影响区扩展;侧面连接接头的裂纹起裂位于焊脚部位。采用扫描电子显微镜对疲劳断裂机理进行分析。疲劳断口由准解理或解理台阶组成,均为脆性断裂,断口中存在二次裂纹,对接接头中存在疲劳条纹,其间距约为5μm。     

AZ31B镁合金在模拟流动海水中的腐蚀行为

利用质量损失法及X射线衍射（XRD）、扫描电镜（SEM）测试手段研究了铸态和挤压态AZ31B镁合金在模拟流动海水中浸泡12 h的腐蚀行为及随流速变化的规律。试验结果表明,AZ31B铸态镁合金试样的耐蚀性要远大于挤压态试样,且二者的腐蚀速率随搅拌速度增加的变化趋势有所不同：铸态试样的腐蚀速率随搅拌速度的增加近似呈线性上升,而挤压态试样的腐蚀速率随搅拌速度的增加而先增大后下降。     

Mo-Zr合金烧结致密化行为及组织与性能研究

在含有不同氟离子浓度的硅酸钠电解液体系中,采用恒压微弧氧化技术对AZ31镁合金进行表面处理,通过XRD、SEM、EDS等研究镁合金表面微弧氧化膜层形貌和相结构特征,探讨氟离子对膜层形成的影响规律.研究结果表明:随着氟离子浓度的增加,膜层微孔数量逐渐减少,微孔孔径逐渐变大且分布均匀,但氟离子浓度过高时,膜层缺陷增多,出现微裂纹和局部孔径较大的微孔;微弧氧化膜层主要由MgAl2O4和MgSiO3组成,其含量随着氟离子浓度的变化而变化,当氟离子浓度范围为2～4 g/L时微弧氧化膜中MgAl2O4和MgSiO3的含量最高;动电位极化曲线表明微弧氧化膜的耐腐蚀性能也随之呈先增后减的趋势.     

Corrosion fatigue behavior of the high-strength magnesium alloy AZ 80

The fatigue performance of the high-strength magnesium alloy AZ 80 is studied in air as well as in aqueous 0.5 and 3.5% NaCl solutions. The effect of mechanical surface treatments, specifically mechanical polishing, shot peening, and roller burnishing on the S-N curves, is investigated using an electropolished surface as a reference. While mechanical polishing as well as shot peening improves fatigue performance in air, no improvement is observed in NaCl solutions. However, roller burnishing, which combines a smooth surface finish with residual compressive stresses in sufficient depths, leads to outstanding fatigue performance even in 3.5% NaCl solution.     

Preparation and corrosion resistance of superhydrophobic coatings on AZ31 magnesium alloy

In order to improve the corrosion resistance of the Mg alloys, the superhydrophobic coatings on AZ31 Mg alloy were prepared by a two-step process of micro-arc oxidation treatment and superhydrophobic treatment in stearic acid ethanol solution. The effects of voltages, frequencies and treatment time on the contact angle of the superhydrophobic treated sample were investigated. The results showed that with increasing the voltage, frequency and treatment time, all of the contact angles of the superhydrophobic treated sample increased first, and then decreased, reaching the maximum values at 350 V, 1000 Hz and 5 min, respectively. The optimal superhydrophobic coating was mainly composed of MgO and Mg₂SiO₄ phases, with the pore diameter of ～900 nm, the thickness of ～6.86 μm and the contact angle of 156.96°. The corrosion current density of the superhydrophobic AZ31 sample decreased by three orders of magnitude, and the amount of hydrogen evolution decreased by 94.77% compared with that of the AZ31 substrate sample.     

Phosphating process of AZ31 magnesium alloy and corrosion resistance of coatings

1 Introduction Magnesium alloys are relatively light structural materials, with excellent physical and mechanical properties,such as low densityand high specific strength, excellent castability and good machinability. These properties make them ideal cand…     

活性剂MATB-I铺设量对镁合金焊接的影响(Ⅰ)

从焊缝成形质量、熔深、合金元素对焊缝作用角度,选择活性剂组元,设计活性剂MATB-I配方,研究焊接电弧形态、焊缝成形和焊接接头金相组织。研究表明:随着活性剂铺设量增加,电弧能量密度迅速增大,电弧收缩力迅速增强,电弧体积扩展,焊缝表面质量逐渐变差,熔宽逐渐增加,焊缝熔深明显增加,最大熔深大于6.30 mm;焊接接头各区晶粒体积和均匀度不一,与焊接外部因素(母材供货质量、焊接输入热量和冷却速度)和内部因素(不规则晶粒储能、晶粒变为球状时释放能量、液态金属结晶形核和晶粒长大速度等)有关。     

Effect of Na2B4O7 on iron reduction in magnesium alloys AZ31 and AZ91

Effect of Na2B4O7, a new iron reduction agent, on iron reduction in magnesium alloys AZ31 and AZ91 was studied. The iron contents in the magnesium alloy AZ31 and AZ91 reduce dramatically to less than 0.002% （mass fraction） with the increasing addition of Na2B4O7, and the corrosion resistance of the alloys was greatly improved. According to the thermodynamic analysis and the iron and boron distributions in different parts of the alloy melts, it can be inferred that the mechanism for iron reduction in magnesium alloys by Na2B4O7 processing is that boron atoms combine with iron atoms and settle down in the melting sludge. The XRD result confirms it.     

Temperature evolution and fatigue life evaluation of AZ31B magnesium alloy based on infrared thermography

The surface temperature of extruded AZ31B alloy plate was measured by infrared thermograph in air during tension and high-cycle fatigue tests. The mechanism of heat production was discussed and the value of critical fatigue damage temperature was calculated according to the P—ΔT curve. Results show that the variation trend of temperature is different between tension and fatigue tests. The temperature evolution in tension test consists of four stages: linear decrease, reverse linear increase, abrupt increase, and final drop. The initial decrease of temperature is caused by thermal elastic effect, which is corresponding to the elastic deformation in tension progress. When cyclic loading is above the fatigue limit, the temperature evolution mainly undergoes five stages: initial increase, steep reduction, steady state, abrupt increase, and final drop. The peak temperature in fatigue test is caused by strain hardening that can be used to evaluate the fatigue life of magnesium alloy. The critical temperature variation that causes the fatigue failure is 3.63 K. When ΔT≤3.63 K, the material is safe under cyclic loading. When ΔT>3.63 K, the fatigue life is determined by cycle index and peak temperature.     

AZ91D镁合金微弧氧化膜耐蚀性的试验研究

研究了AZ91D镁合金微弧氧化膜在复合铝酸盐溶液中的耐蚀性。利用X射线衍射（XRD）和扫描电子显微镜（SEM）分析了AZ91D镁合金微弧氧化膜的物相和表面形貌;利用IM6e型电化学工作站测量了氧化膜的电化学阻抗和稳态电流／电位极化曲线;利用CMB-1501B型便携式瞬时腐蚀速度测量仪测量了氧化膜的腐蚀电流密度Icorr和年腐蚀深度MMA。试验结果表明,微弧氧化的镁合金耐蚀性提高了2～3个数量级,镁合金微弧氧化膜主要由MgO、MgAl2O4、Al12Mg17组成。     

Improving the fatigue property of welded joints for AZ31 magnesium alloy by ultrasonic peening treatment

The fatigue property of AZ31 magnesium alloy and its TIG welded joints were investigated. The ultrasonic peening treatment (UPT) was used to improve the fatigue property of the TIG welded joints, which was treated at the weld toe by the UPT process. The test results show that the fatigue strength of the base metal of AZ31 magnesium alloys is 57.8 MPa, and those of the fillet joint and the transverse cross joint are respectively 20.0 MPa and 17.2 MPa at 2×106 cycles. The fatigue strengths of two kinds of welded joints treated by the UPT are respectively 30.3 MPa and 24.7 MPa, which have been improved by 51.5% and 43.6%, respectively. The fatigue life of the fillet joint specimens is prolonged by about 2.74 times and the fatigue life of the transverse cross joint specimens is prolonged by about 1.05 times when the stress range is at 40.0 MPa.