Effects of annealing treatment on microstructure and tensile behavior of the Mg-Zn-Y-Nd alloy

In the present study,the Mg-4Zn-0.6Y-0.5Nd alloy was hot extruded and annealed at 200℃,225℃ and 250℃ for different time to optimize microstructure and mechanical properties.The results exhibit that the dual-size grain structure and linearly distributed secondary phase are the main feature of the as-extruded Mg-Zn-Y-Nd alloy,which can be described as the elongated grain is surrounded by the fine equiaxed grain.Moreover,the as-extruded alloy shows strong{011^(-)0}fiber texture feature,especially for the large elongated grains.The annealing treatment results in static recrystallization,which increases fine equiaxed grains but decreases large elongated grains.In addition,the equiaxed grains formed during the annealing treatment demonstrate relative random orientations,which weaken the{011^(-)0}fiber texture of the alloy.Moreover,during the annealing at 225℃and 250℃,the extension twins begin to form in the alloy and weaken the{011^(-)0}fiber texture of the alloy further.The annealing treatment has little influence on the linearly distributed secondary phase but promotes the coarsening of small precipitates at 250℃.The annealing treatment could increase the yield and ultimate strength,but the elongation decreases,especially at higher temperature.Such a variation can be ascribed to the evolution of texture,grain structure,twinning and precipitation during the annealing treatment.

Effect of annealing treatment on microstructures and properties of austenite-based Fe-28Mn-9Al-0.8C lightweight steel with addition of Cu

The mechanical properties of an austenite-based Fe-Mn-Al-C lightweight steel were improved by co-precipitation of nanoscale Cu-rich and κ-carbide particles.The Fe-28Mn-9Al-0.8C-(0,3)Cu (wt.%) strips were near-rapidly solidified and annealed in the temperature range from 500 ℃ to 700 ℃.The microstructure evolution and mechanical properties of the steel under different annealing processes were studied.Microstructural analysis reveals that nanoscale κ-carbides and Cu-rich particles precipitate in the austenite and ferrite of the steel in this annealing temperature range.Co-precipitation of nanoscale Cu-rich particles and κ-carbides provides an obvious increment in the yield strength.At the annealing temperature of 600 ℃,both the yield strength and ultimate tensile strength of Fe-28Mn-9Al-0.8C-3Cu (wt.%) steel strip are the highest.The total elongation is 25%,which is obviously higher than that of Cu-free steel strips,for the addition of Cu reduces the large sized κ-carbides precipitated along austenite/ferrite interfaces.When the annealing temperature rises to 700 ℃,the strength and ductility of the two steel strips deteriorate due to the formation of massive intergranular κ-carbides precipitated along austenite/ferrite interfaces.It can be concluded that a proper co-precipitation of Cu-rich particles and κ-carbides would improve the properties of austenite-based Fe-Mn-Al-C steel.

Influence of annealing treatment on properties and microstructures of alumina dispersion strengthened copper alloy

Alumina dispersion strengthened copper（ADSC） alloy was produced by internal oxidation. The hardness, ultimate tensile strength and electrical conductivity measurements and microstructure observation on the produced 0.12%ADSC （0.24% Al2O3, mass fraction） and 0.25%ADSC （0.50% Al2O3） subjected to different annealing treatments were conducted. The results show that the microstructure of the produced ADSC is characterized by an uniform distribution of nano-Al2O3 particles in Cu-matrix; the particles range in size from 20 to 50 nm with an interparticle spacing of 30100 nm. The produced 0.12%ADSC can maintain more than 87% hardness retention after 900 ℃, 1 h annealing treatment; the recrystallization can be largely retarded and is not fully completed even after annealing at 1 000 ℃ for 1 h, followed by cold deformation of 84%; local grain growth can be observed after 1 050 ℃, 1 h annealing treatment. The results also show that increasing either the alumina content or cold deformation degree increases the hardness of the produced ADSC.

Effect of pre-annealing treatment on the microstructure and mechanical properties of extruded Al–Zn–Mg–Cu alloy bars

Taking extruded Al–Zn–Mg–Cu alloy(7A04 alloy) bars as the research object, the effect and mechanism of pre-annealing treatments on the microstructure and mechanical properties of the aged alloy bars were investigated. The results show that a pre-annealing treatment at 350°C for 15 h before a T6 treatment substantially reduced the sensitivity of the microstructure and mechanical properties of the extruded 7A04 aluminum alloy specimens toward the extrusion temperature. The average grain sizes of the specimens extruded at 390 and 430°C after T6 treatment were 3.4 and 8.1 μm, respectively, and their elongations to failure were 7.0% and 9.2%, respectively. However, after pre-annealing + T6 treatment, the differences in both the grain sizes and the elongations of the specimens became small, i.e., their average grain sizes were 3.2 and 3.8 μm and their elongations were 12.0% and 13.3%, respectively. For the specimens extruded at the same temperature, pre-annealing treatment obviously improved the plasticity of the alloy, which is attributed to an increase in soft texture or to grain refinement in the specimens as a result of the pre-annealing + T6 treatment.

The effect of annealing treatment on the microstructures and mechanical properties of cold-sprayed nickel coating

The effect of annealing treatment on the microstructures and mechanical properties of cold-sprayed Ni coating was investigated by conducting micro-hardness and tensile tests and using a normal optical microscope （OM） ,a scanning electron microscope （ SEM）, a transmission electron microscope （TEM） and an electron probe X-ray microanalyzer （EPMA）. The results show that following the increase of the annealing temperature ,the micro-hardness of cold-sprayed Ni coating decreases and the elongation after fracture increases, while the tensile strength increases before decreasing. The tensile deformation and fracture behavior change from a typical brittle fracture to a hybrid brittle and ductile fracture, then to a typical ductile failure. It is found that when annealed at an elevated temperature （ e. g. 900℃ ） ,the grains tend to grow abnormally with the oxides spheroidizing and the defects agglomerating at the interfaces, causing the tensile strength reduction of the cold-sprayed nickel coating. It is also pointed out that the tensile strength of the cold-sprayed Ni coating can be significantly improved by the appropriate annealing procedures, but the elongation after fracture cannot be clearly increased because it is difficult to eliminate the main defects in the coating by the following heat treatments.

Influence of Annealing Treatment on Microstructure Evolution and Mechanical Property of Friction Stir Weld AZ31 Mg Alloys

In order to improve microstructure distribution and mechanical properties of Mg alloy joint by annealing treatment, die-casting AZ31 Mg alloy was successfully welded at rotation speed of 1 400 rpm and travel speed of 200 mm/min. The welded joints were annealed at 150-300 ℃ for 15-120 min and then were subjected to transverse tensile. The microstructure of annealed joints was analyzed by optical microscopy and electron backscatter diffraction. The experimental results indicate that(0001) texture intensity in stir zone significantly reduces and sharp transition of grain size is relieved in the interface between stir zone and thermo-mechanically affected zone after annealed at 200 ℃ for 30 min. Meanwhile, the elongation is increased from 7.5% to 13.0% and strength is increased slightly. It is because that annealing treatment can inhibit twin transformation and retain its ability to coordinate deformation during tensile deformation, which contributes to the improvement of plasticity. In addition, annealing treatment can increase the width of interfacial transition zone and lead to gradual transition of grain size between the SZ and TMAZ, which balances dislocation diffusion rate in different zone.

Effect of annealing treatment on electrochemical property of LiNi_(0.5)Mn_(1.5)O_4 spinel

LiNi0.5Mn1.5O4 was prepared under different cooling conditions. The electrochemical properties of LiNi0.5Mn1.5O4 prepared under different cooling conditions were investigated. The results show that LiNi0.5Mn1.5O4 synthesized with or without annealing treatment has similar X-ray diffraction patterns that can be indexed to cubic spinel structure. The mass loss occurring above 650 ℃ during the heating process can be mostly gained during the cooling process. LiNi0.5Mn1.5O4 synthesized with an annealing treatment exhibits almost one voltage plateau at around 4.7 V and higher capacity with a quick fading upon cycling, whereas LiNi0.5Mn1.5O4 synthesized without annealing treatment shows two voltage plateaus at around 4.1 and 4.7 V and superior capacity retention upon cycling both at rates of 1/7C and 1C, though the capacity is not high.

Impact of Annealing Treatment on the Behaviour of Titanium Dioxide Nanotube Layers

In this work, we study the influence of the annealing treatment on the behaviour of titanium dioxide nanotube layers. The heat treatment protocol is actually the key parameter to induce stable oxide layers and needs to be better understood. Nanotube layers were prepared by electrochemical anodization of Ti foil in 0.4 wt% hydrofluoric acid solution during 20 minutes and then annealed in air atmosphere. In-situ X-ray diffraction analysis, coupled with thermogravimetry, gives us an inside on the oxidation behaviour of titanium dioxide nanotube layers compared to bulk reference samples. Structural studies were performed at 700°C for 12 h in order to follow the time consequences on the oxidation of the material, in sufficient stability conditions. In-situ XRD brought to light that the amorphous oxide layer induced by anodization is responsible for the simultaneous growths of anatase and rutile phase during the first 30 minutes of annealing while the bulk sample oxidation leads to the nucleation of a small amount of anatase TiO2. The initial amorphous oxide layer created by anodization is also responsible for the delay in crystallization compared to the bulk sample. Thermogravimetric analysis exhibits parabolic shape of the mass gain for both anodized and bulk sample;this kinetics is caused by the formation of a rutile external protective layer, as depicted by the associated in-situ XRD diffractograms. We recorded that titanium dioxide nanotube layers exhibit a lower mean mass gain than the bulk, because of the presence of an initial amorphous oxide layer on anodized samples. In-situ XRD results also provide accurate information concerning the sub-layers behavior during the annealing treatment for the bulk and nanostructured layer. Anatase crystallites are mainly localized at the interface oxide layer-metal and the rutile is at the external interface. Sample surface topography was characterized using scanning electron microscopy (SEM). As a probe of the photoactivity of the annealed TiO2 nanotube layers, degradation of an acid orange 7 (AO7) dye solution and 4-chlorophenol under UV irradiation (at 365 nm) were performed. Such titanium dioxide nanotube layers show an efficient photocatalytic activity and the analytical results confirm the degradation mechanism of the 4-chlorophenol reported elsewhere.

Effect of Cu doping and annealing treatment on the microstructure and mag-netic properties of nanocrystalline single-phase Nd-Fe-B alloys

The effects of Cu addition and annealing treatment on the magnetic properties and microstructure of Ndl2.3Fe81.7-xCuxB6 （x=0-1.2） ribbons melt-spun and annealed were systematically investigated by the methods of vibrating sample magnetometer （VSM）, X-ray diffraction （XRD）, and transmission electron microscopy （TEM）. Optimum magnetic properties were achieved by annealing melt-spun Nd12.3Fe81.5Cu0.2B6 ribbons at 550℃ for 15 min, which only contained Nd2Fe14B phase. The remanence, coercive force, and maximum energy product increase by 18.4%, 36.2%, and 49% respectively compared with those of Cu-free samples. The sig- nificant improvement in magnetic properties originates from the freer grains of the samples by introducing Cu, which leads to the stronger exchange-coupling between neighboring grains.

Effect of annealing treatment on optical and electrical properties of ZnO films

The ZnO-Al films were prepared by R.F. magnetron sputtering system using a Zn-Al target (with purity of (99.99%).) The obtained films were characterized by X-ray diffraction, SEM and optical and electrical measurements. The experimental results show that the properties of ZnO films can be further improved by annealing treatment. The crystallinity of ZnO films becomes better, and the optical gap energy is decreased, but thermoelectric power is enhanced after heat treatment. The optical gap energy decreases from 3.75 eV to 3.68 eV when the annealing temperature increases from 25 ℃ to 400 ℃.This can be ascribed to the decrease of carrier concentration, resulting in Burstein shift.

退火态CFR镁/铝复合板界面形貌与力学性能研究

通过对波-平轧制镁/铝复合板进行退火处理,研究了退火温度和退火时间对镁/铝复合板界面微观组织和力学性能的影响规律。结果表明, 200℃/30 min退火平直镁/铝复合板新结合界面生成薄的Mg_(17)Al_(12)相扩散层,这可以促进界面冶金结合,提升界面结合强度。当250℃/30 min退火时,新结合界面迅速扩展,进一步形成由Mg_(17)Al_(12)相和Mg_(2)Al_(3)相共同构成的IMCs层。当退火温度升高到300℃时,界面整体形成连续分布的IMCs层,退火温度越高或退火时间越长, IMCs层厚度越大。高温退火处理时,强塑性变形可以加速波谷位置界面原子间的扩散,导致同种化合物波谷位置的生长激活能小于波峰位置,从而造成波谷扩散层厚度大于波峰。退火态镁/铝复合板弯曲测试后,界面无分层、基体无脱落。随着退化温度的升高,平直镁/铝复合板高温拉伸抗拉强度下降,而断裂伸长率增加。

激光选区熔化Ti-6Al-4V合金的微纳压痕尺寸效应

目的研究不同状态激光选区熔化Ti-6Al-4V合金的纳米压痕尺寸效应。方法对原始态合金分别进行600、700、800、900℃退火处理,利用扫描电子显微镜观察原始态和4种退火态合金的显微组织。基于纳米压痕技术测量原始态及4种退火态合金的纳米硬度和弹性模量。基于比例试样阻力模型、Nix-Gao模型和Meyer定律对纳米硬度进行函数拟合。结果随着退火温度的升高,原始态组织从魏氏体逐渐演变为网篮组织。5种形态的Ti-6Al-4V合金的硬度和弹性模量均出现随压入深度的增加而减小的现象,表现出典型的压痕尺寸效应,基于试验测得的原始态及4种退火态合金的纳米硬度分别为3.66、4.36、3.96、3.88、4.77 GPa,弹性模量分别为113.1、125.2、102.1、100.3、108.7 GPa;基于比例试样阻力模型计算的纳米硬度分别为3.53、4.34、3.92、3.52、4.04 GPa;基于Nix-Gao模型计算的纳米硬度分别为3.68、3.94、4.07、3.85、4.47 GPa;基于Meyer定律拟合出的迈耶指数分别为1.75、1.86、1.82、1.80、1.81,均小于2,均表现为正压痕尺寸效应。结论激光选区熔化Ti-6Al-4V合金的硬度及弹性模量均有典型的压痕尺寸效应;3种模型均能较好地描述原始态和退火态合金的压痕尺寸效应,Nix-Gao模型直接建立了纳米硬度和压痕深度的关系,其拟合结果更接近于试验结果,计算的硬度值也最为准确。

高温对含氢DLC涂层的微观结构及力学性能的影响

目的针对含氢DLC涂层热稳定性很差的问题,探究高温下含氢DLC涂层的微观组织变化特征,以及高温对其力学性能的影响。方法采用等离子体强化化学气相沉积(Plasma Enhanced Chemical Vapor Deposition,PECVD)在S136模具不锈钢表面沉积以Si为过渡层的含氢DLC复合涂层,利用光学显微镜、扫描电镜、拉曼光谱、X射线电子衍射仪、三维轮廓仪研究DLC涂层的微观结构,采用划痕测试仪、往复式摩擦磨损试验机、纳米压痕仪研究DLC涂层的力学性能,并通过LAMMPS软件,利用液相淬火法建立含氢DLC模型,模拟分析经高温处理后涂层的组织变化特征和纳米压痕行为。结果在400℃、2 h的退火条件下,拉曼谱峰强度ID/IG由未退火的0.7增至1.5,涂层发生了石墨化转变,同时基线斜率下降,H元素析出;XPS结果表明,在此条件下涂层中sp^(2)杂化组织相对增加,氧元素增多,涂层粗糙度增大;在600℃、2 h退火条件下,DLC发生了严重氧化,LAMMPS模拟结果表明,在400℃高温下涂层的分子键长变短,表明sp3杂化组织在高温下吸收能量,并向sp^(2)杂化转变。纳米压痕模拟结果显示,在400℃下退火后,涂层的硬度下降。结论在400℃下退火处理后,涂层中的H元素释放,涂层内应力减小,保证了涂层的强度;在600℃退火条件下,过渡层的Si和DLC在高温下形成了C—Si键,使得DLC薄膜部分被保留;LAMMPS模拟结果表明,在高温下涂层发生了石墨化转变,涂层的硬度减小。

退火处理对异种钢激光焊接头组织及性能的影响

目的通过研究相同时间不同退火温度下304/Q345激光焊接头的组织和性能,得到优化后的退火处理制度,为制定异种钢激光焊退火工艺提供一定的理论指导和技术支撑。方法基于前期大量试验,在激光功率和离焦量不变的情况下,调节焊接速度由15 mm/s到35 mm/s,通过改变焊接速度获得性能优异的焊接接头。由于异种钢物理化学性能差异较大,接头组织不均匀,因此还需对激光焊接头进行退火处理。结果焊缝区显微组织由板条马氏体与残余奥氏体组成,Q345低碳钢热影响区显微组织为多面体状铁素体与黑色珠光体,其中铁素体含量更多,304奥氏体不锈钢热影响区在奥氏体晶界上析出了铁素体。不同退火温度下碳元素均由Q345低碳钢侧向焊缝迁移,在Q345低碳钢侧形成脱碳层,在焊缝中形成黑色条带状增碳层。随着退火处理温度的升高,峰值温度升高,高温停留时间变长,碳迁移强度随之增加,黑色条带状区域增碳层宽度增大。拉伸性能测试结果表明,试样均断裂于Q345母材一侧,且断口存在韧窝,属于典型韧性断裂。此外,焊缝区硬度(390HV左右)最高,热影响区硬度(300HV)次之,母材的硬度(130HV左右)最低。结论在给定试验参数范围内,优化后的最佳退火工艺参数为550℃-1.5 h。

3D打印技术在航空伞箱制造中的应用

阐述了国内外3D打印技术研究与应用现状和激光选区熔化技术成形特点。以航空航天制造领域铝合金薄壁伞箱为典型案例,围绕激光选区熔化工艺中如何控制变形零件、保证质量为关键点,从添加辅助支撑、工艺参数设置、退火处理及三维扫描检测等方面开展应用研究。结果表明:通过科学设计辅助支撑、合理设置工艺参数和规范热处理,能够减少激光选区熔化中零件变形及其他缺陷产生。

IAZO薄膜晶体管的制备与性能研究

为了探究退火温度对IAZO薄膜晶体管器件光电性能的影响,采用射频溅射单溅射法,并在(400~700)℃的范围内制备了一系列真空退火后的IAZO薄膜晶体管。分别对IAZO薄膜表面形貌、内部结构、元素组成和价态组成进行分析,采用半导体参数仪及搭配的探针台测试电学性能测试。采用紫外可见分光光度计测试薄膜透过率。结果表明,随着退火温度的升高,器件的电学性能先呈现上升趋势,达到峰值后开始下降。在500 ℃真空退火1 h后,IAZO TFT饱和迁移率为0.18 cm2/(V·s)、阈值电压为3.35 V、亚阈值摆幅为0.10 V/decade、开关比为1.13*108。IAZO薄膜透光率达到90 %以上、光学带隙达到4.1 eV,器件性能达到最佳。

相对分子质量和退火处理对聚碳酸酯力/热性能的影响

文中研究了不同相对分子质量聚碳酸酯在经历退火处理后力学性能和热性能的变化,深入分析了相对分子质量和退火处理的影响机制。结果表明,高分子量聚碳酸酯未退火状态下抗拉伸断裂性能和冲击性能更优,相对分子质量降低和退火处理会提升拉伸强度与弯曲性能。光弹应力分析显示,高分子量未退火聚碳酸酯的残余应力高,冲击断面表现为韧性断裂,对应冲击强度高。动态力学热分析和差示扫描量热法研究发现,随着相对分子质量增大,聚碳酸酯的玻璃化转变温度升高,链段运动更加趋于弹性响应。

轧制退火工艺对高碳含量孪晶诱发塑性钢拉伸变形行为的影响

以Fe-18Mn-1.0C高碳含量TWIP钢为研究对象,利用单向拉伸试验、光学显微镜和扫描电子显微镜研究了冷轧压下量和退火温度对高碳TWIP钢拉伸变形行为的影响。结果表明,随着压下量的增加,试验钢中产生大量变形组织,在轧制变形组织作用下,Fe-18Mn-1.0C钢的屈服强度及抗拉强度显著提高但塑性降低;冷轧高碳TWIP钢拉伸过程中产生动态应变时效(DSA)现象,随着压下量的增加,锯齿幅度减弱,锯齿数量减少,DSA现象减弱;对冷轧40%试样进行不同温度的退火处理,发现随退火温度的升高,试样屈服强度降低,当退火温度超过400℃时,抗拉强度明显下降,伸长率出现先增加后降低的现象;对于高碳TWIP钢,当退火温度超过400℃时,碳化物快速析出是其抗拉强度及伸长率降低的主要原因。

Cr4Mo4V钢球的淬火混晶组织细化试验研究

对出现混晶组织的Cr4Mo4V淬回火钢球分别进行亚临界退火、等温退火处理,然后再经1115℃淬火后观察晶粒改善情况。利用X射线衍射方法分析不同状态Cr4Mo4V试样的微观畸变;利用光镜、扫描电镜对比分析各试样中的二次碳化物形态与分布特点。结果表明,Cr4Mo4V钢球混晶组织有所改善,但晶粒依然粗大;中间退火并没有有效消除淬火粗晶的遗传现象。有迹象显示:粗晶的遗传与淬火未溶碳化物和再次淬火前组织中二次碳化物的方向性分布密切相关。

热处理技术对3D打印钛合金试件机械性能的影响

背景:近年来,增材制造(又称3D打印)逐渐成为制作可摘局部义齿钛合金支架的主流方式。热处理作为改善3D打印钛合金支架机械性能的重要方法而成为目前的关注热点。目的:总结目前应用于3D打印钛合金试件的主要热处理技术(包括退火处理、固溶时效处理、热等静压处理及其他热处理)以及这些热处理技术对3D打印钛合金试件机械性能、微观结构的影响,为改进可摘局部义齿钛合金支架的热处理技术提供理论依据。方法:采用计算机检索中国知网、PubMed和ScienceDirect数据库中有关3D打印钛合金热处理试件的文献资料,检索时限为2012-2023年,根据纳入和排除标准,最终选取61篇文献进行综述分析。结果与结论:①使用常规退火技术处理3D打印钛合金试件,使其在500-900℃下保持2-4 h,能有效增加3D打印钛合金试件的延伸率。②固溶时效处理相较于常规退火技术更复杂,固溶时效处理后的钛合金试件在屈服强度方面表现突出,并且有更好的耐腐蚀性;但固溶时效处理后的3D打印钛合金试件在延伸性方面没有优势。③热等静压处理可以减少3D打印钛合金试件的内部缺陷,可明显增加3D打印钛合金试件延伸率,并增加其疲劳寿命。④快速热处理可以明显提高3D打印钛合金试件的延伸率,并且速度更快,在延伸率提升和热处理效率方面,比以往常规的退火更具优势。⑤循环热处理对3D打印钛合金试件延伸率的提升超过了常规退火,循环热处理可明显改善3D打印钛合金试件的晶粒结构,但热处理时间过长,效率较低。