基于VC++的金属凝固过程微观组织演变的可视化研究

以Al-4%Cu合金为例，利用热焓法处理结晶潜热，再根据相变热传导的等效热容法有限元理论，求解了该合金凝固过程的温度场分布；结合连续形核模型和枝晶尖端生长的动力学模型，进行了温度场与晶粒组织形成过程的耦合模拟；通过调用VC＋＋的图形设备接口函数库和设备环境功能，实现了晶粒形成过程的计算机可视化。     

Ti-6Al-4V合金在真空中的干滑动磨损行为

在真空(10^-^5Pa)条件下对Ti-6Al-4V合金进行了系统的磨损性能测试，研究了载荷和滑动速度对Ti-6Al-4V合金磨损率的影响．对Ti-6Al-4V合金的磨损表面进行了显微组织分析．实验结果表明，Ti-6Al-4V合金的磨损率随载荷和滑动速度的升高而增加．磨损表面具有层状结构的舌状形貌特征，分析表明这是Ti-6Al-4V合金表面通过接触点处材料的被推挤和碾压过程形成了特殊的变形堆砌层的结果．显微组织分析显示，这种变形堆砌层具有50—100nm尺寸的细小显微组织结构和50mm以上的厚度．     

异步轧制AZ31镁合金板材室温冲压性能研究

文章主要对异步轧制AZ31镁合金板材室温冲压性能进行了研究,以探讨提高镁合金板材冲压性能的途径。结果表明,异步轧制有利于板材的晶粒细化,其晶粒尺寸约为7.6μm,明显小于普通轧制板材的12.5μm;而由于异步轧制过程中剪切变形的作用,异步轧制使板材的(0002)基面晶粒取向减弱;与普通轧制相比,异步轧制板材的应变硬化能力增加,屈服强度降低,制耳参数减小,但塑性应变比也降低,这可归因于异步轧制所导致的晶粒细化和晶粒取向的改变。     

电脉冲孕育处理对Al-Cu-Mn合金时效过程的影响

考察了不同电脉冲孕育处理参数对Al-Cu-Mn合金时效过程的影响，结果表明：电脉冲孕育处理加速了A1．5％Cu-0．8％Mn合金时效进程，缩短了时效时间，使合金最大显微硬度较未处理试样提高了13％～17％；但不同的电脉冲参数影响时效过程的程度不同，一定范围内，500V电压，30s处理时间，频率为3Hz的电脉冲参数在740℃处理时，合金时效后的显微硬度最高。     

Evaluation of hydrogen absorption properties of Ti–0.2 mass% Pd alloy in fluoride solutions

The hydrogen absorption properties of Ti–0.2 mass% Pd (Ti–0.2Pd) alloy in 2.0% and 0.2% acidulated phosphate fluoride (APF) and neutral 2.0% NaF solutions (25 °C) has been evaluated by hydrogen thermal desorption analysis. During the early stage of immersion (120 h) in the 2.0% APF solution, the amount of absorbed hydrogen was lower than 500 mass ppm. A thermal desorption of hydrogen primary appearing with a peak at 500–600 °C and a broad desorption ranging from 100 to 400 °C were observed. In the 0.2% APF solution, the amount of absorbed hydrogen saturated at 100–200 mass ppm; the thermal desorption of hydrogen appeared with a single peak at 550 °C. In the 2.0% NaF solution, hydrogen absorption was negligible even after 1000 h of immersion, although corrosion pits were observed. The results of the present study suggest that the hydrogen absorption of Ti–0.2Pd alloy, as compared with commercial pure titanium, is suppressed in fluoride solutions.     

热变形参数对Ti-15-3合金显微组织的影响及预测

通过等温压缩试验和金相分析研究了热变形参数对Ti-15-3(Ti-15V-3Cr-3Sn-3Al）合金固溶处理后显微组织的影响，等效晶粒尺寸随变形温度升高而增大，随变形程度和变形速率增加而减小，再结晶程度随变形温度升高而减小，随变形程度和变形速率增加而增大，采用人工神经网络的方法建立了等效晶粒尺寸及再结晶晶粒体积百分数与变形程度，变形速率和变形温度间的数学模型，预测值与实测值吻合较好，表明该方法很好地预测热变形参数对Ti-15-3合金固溶处理后显微组织的影响。     

Novel approach of LY12 alloy brazing

The LY12 Al alloy was brazed with the adoption of the improved KF-CsF-AlF3 flux matching Ag-Al-Cu-Zn filler metal. The shear strength of brazed joint could reach 80% of that of the substrate and the tensile strength of butt brazed joint will be 70% of that of the substrate. This was the great progress against the traditional claim that Al alloy reinforced by heat treatment could not be brazed. The experimental results and theoretical analysis had proved that it was the key issue to remove the MgO oxide film below 503℃. The addition of rare earth La was the effective way to obtain better mechanical properties of the filler metal as well as brazed joints.     

表面处理状态对Fecralloy合金氧化膜完整性的影响

研究了表面粗糙度对Fecralloy (Fe 2 2Cr 5Al 0 .3Y ,质量分数 ,% )合金在 12 0 0℃空气中循环氧化生成表面氧化膜完整性的影响。采用SEM技术着重研究了合金表面氧化膜的性质和特点。结果表明合金表面粗糙度对Fecralloy合金表面氧化膜的完整性有重要的影响 ,初始合金表面粗糙度越大 ,氧化膜越容易开裂。讨论了合金表面粗糙度对氧化膜开裂行为的影响。     

Effect of second phase precipitation behavior on mechanical properties of casting Al-Cu alloys

The effect of the second phase precipitation behavior on the mechanical properties and fracture behavior of the modified casting Al-Cu alloys was investigated. The tensile strength of the alloys increases firstly and then decreases due to the appearance of θ＇ precipitation phases, which increases firstly and then become coarser with the aging time increasing from 10 h to 20 h at 155 ℃. The strength of the alloys reaches the peak, resulting from ,Ω and θ＇ precipitation phases, and decreases due to ,Ω phases becoming coarser and θ＇ precipitation decreasing with the aging time increasing from 10 h to 20 h at 165 ℃. ,θ phase becoming coarser and θ＇ precipitation decreasing result in the strength of the alloys drastically decreasing after aging at 175 ℃ for 20 h. The ductility remains high level with increasing aging time at 155 ℃. The ductility irregularly changes as aging time prolongs at 165 ℃. The ductility is very low and at the same time gradually decreases with increasing aging time at 175 ℃. The Al-Cu alloy with a promising combination of tensile strength and ductility of about 474 MPa and 12.0% after aging at 165℃ for 10 h is due to a dense, uniform distribution of,Ω precipitation phases together with a heterogeneous distribution of θ＇ precipitations.     

MICROSCOPIC PHASE-FIELD SIMULATION COUPLED WITH ELASTIC STRAIN ENERGY FOR γ′(Ni3Al) PRICIPITATION IN Ni-Al ALLOY

基于微观相场动力学模型和微观弹性能理论,对Ni-Al合金中沉淀相Ni3Al(γ′)形貌演化、早期沉淀机制和后期粗化过程进行了原子层面的计算机模拟.结果表明:沉淀过程中γ′相形貌由早期随机分布的圆形或不规则状逐渐向方形转变,其排列的取向性也越来越明显,最后形成周边圆滑的长方块状颗粒,沿[10]和[01]弹性"软"方向规则排列.弹性应变能作用下的粗化过程遵循优先选择的原则,位于弹性"软"方向上的颗粒不断长大和粗化,位于弹性"软"方向外的颗粒逐渐消失,沉淀后期在基体中形成高度择优取向的微观组织.低浓度Ni-Al合金中γ′相的早期沉淀机制为非经典形核长大机制,其演化序列为:过饱和固溶体→非化学计量比有序相→化学计量比平衡γ′相→长大.