TiZrNiCuBe块体非晶合金的蠕变行为

发布时间：2018-07-10 15:46

本文选题：Ti基块体非晶合金 + 拉伸蠕变行为　；参考：《哈尔滨工业大学》2017年硕士论文

【摘要】：块体非晶合金作为新材料具有优异的力学性能。本论文的实验研究对象是铸态、退火态以及不同晶化分数的Ti_(40)Zr_(25)Ni_3Cu_(12)Be_(20)非晶合金,探究了铸态非晶合金的拉伸蠕变行为及其机理,并研究了不同退火态和晶化态的Ti_(40)Zr_(25)Ni_3Cu_(12)Be_(20)非晶合金的纳米压痕蠕变行为,对Ti_(40)Zr_(25)Ni_3Cu_(12)Be_(20)非晶合金的压痕蠕变行为机理进行了探讨。借助透射电子显微镜(TEM)对拉伸蠕变测试后Ti_(40)Zr_(25)Ni_3Cu_(12)Be_(20)非晶合金样品的变形区和夹持区进行了观察。发现随外加应力增加和外加温度的升高,非晶合金样品的夹持区保持了较好的非晶态状态,变形区晶化程度则不断增加,变形区析出纳米晶。观察了退火态非晶合金样品,发现其微观结构有序度随退火温度的增加而增加,局部出现尺寸为5~10nm的纳米晶。观察了晶化态非晶合金样品,发现样品析出纳米晶的尺寸随晶化程度的增加而增加。结合拉伸蠕变曲线、X射线衍射(XRD)分析曲线综合讨论了非晶合金的拉伸蠕变行为。拉伸结果表明Ti_(40)Zr_(25)Ni_3Cu_(12)Be_(20)非晶合金主要方式为脆断。蠕变过程主要受到局部非均匀剪切应力的作用。拉伸过程中外加载荷对非晶合金原子有序度的影响明显。对拉伸断口的形貌进行了扫描电子显微镜(SEM)分析,断口展现出明显的非晶脆断形貌(河流花样),随外加应力和温度的增加,断口河流花样的数量和密度也随之增加。外加条件为670K、200MPa时断口出现“熔滴”的情况。借助差示扫描量热法(DSC)对拉伸蠕变样品断口区和夹持区进行相关分析,确定了不同应力和温度条件下断口区和夹持区的晶化程度。结果认为随外加应力和温度的增加材料的晶化程度随之增加,当外加条件为670K、200MPa时材料断口区晶化程度最为严重。结合纳米压痕蠕变曲线、XRD曲线、DSC曲线、TEM观察综合分析了退火态非晶合金的纳米压痕蠕变行为。随退火温度的增加,Ti_(40)Zr_(25)Ni_3Cu_(12)Be_(20)非晶合金样品的有序度随之增加,且抗蠕变性能增加,而铸态非晶合金展现出最差的抗蠕变性能,320℃退火一小时抗蠕变性能为研究样品中最好。XRD结果显示样品保持良好的非晶态,TEM显示样品随退火温度的增加未发生晶化现象,原子有序度随之增加。另外,随外加载荷的增加,样品的抗蠕变性能随之发生变化,纳米压痕金刚石压头压入样品表面的深度随外加载荷的增加而增加,保载300s时间内蠕变位移量随载荷增加而增加,稳态蠕变阶段非晶合金的稳态蠕变速率随外加载荷的增加而增加。系统开展了晶化态非晶合金的纳米压痕蠕变行为。XRD曲线显示经过不同程度晶化处理后,样品发生了不同程度的晶化,DSC曲线得到了其精确的晶化分数。TEM图和电子衍射图结果显示材料在晶化处理后出现大量的纳米晶粒。纳米压痕蠕变曲线结果显示,在同载荷条件下,随晶化程度的增加材料的抗蠕变性能增强。在晶化程度相同时,样品对外加载荷依赖性强,随外加载荷的增加,压头压入表面的深度增加,蠕变稳态阶段的蠕变位移量增加,稳态蠕变速率增加。
[Abstract]:The bulk amorphous alloys have excellent mechanical properties as new materials. The experimental study in this paper is Ti_ (40) Zr_ (25) Ni_3Cu_ (12) Be_ (20) amorphous alloy as cast state, annealed state and crystallization fraction. The tensile creep behavior and its mechanism of as cast amorphous alloys are investigated and the Ti_ (40) Zr_ (25) (40) Zr_ (25) of different annealed and crystalline states are studied. The indentation creep behavior of Ni_3Cu_ (12) Be_ (20) amorphous alloy was investigated in the indentation creep behavior of Ti_ (40) Zr_ (25) Ni_3Cu_ (12) Be_ (20) amorphous alloy. By means of transmission electron microscopy (TEM), the deformation zone and holding area of Ti_ (40) Zr_ (25) Ni_3Cu_ (12) Be_ (20) amorphous alloy samples after tensile creep test were observed. With the increase of external stress and the increase of external temperature, the holding area of amorphous alloy samples keeps a better amorphous state, the crystallization degree of the deformation zone is increasing and the nanocrystalline is precipitated in the deformation zone. The annealed amorphous alloy samples are observed and the microstructure order degree increases with the increase of annealing temperature, and the local appearance size is 5~. 10nm nanocrystals. The crystalline amorphous alloy samples were observed. It was found that the size of the precipitated nanocrystals increased with the increase of the crystallization degree. The tensile creep behavior of amorphous alloys was discussed by the X ray diffraction (XRD) analysis curve combined with the tensile creep curve. The tensile results showed that Ti_ (40) Zr_ (25) Ni_3Cu_ (12) Be_ (20) amorphous alloy was the main square alloy. The creep process is mainly affected by local nonuniform shear stress. The effect of loading on the order degree of amorphous alloy atoms is obvious in the process of stretching. The morphology of the tensile fracture surface is analyzed by scanning electron microscope (SEM). The fracture surface shows obvious amorphous brittle fracture morphology (river pattern), with the external stress and temperature. In addition, the number and density of the fractured river pattern increased with the addition of the addition of "droplets" on the fracture surface at 670K and 200MPa. By means of differential scanning calorimetry (DSC), the correlation analysis between the fracture zone and the holding area of the tensile creep samples was carried out, and the crystallization degree of the fracture zone and the holding area under different stress and temperature conditions was determined. It is considered that the crystallization degree of the material increases with the added stress and temperature. When the external condition is 670K and 200MPa, the crystallization degree of the fracture zone is the most serious. The nano indentation creep behavior of the annealed amorphous alloy is synthetically analyzed with the nano indentation creep curve, the XRD curve, the DSC curve and the TEM observation. With the increase of annealing temperature, Ti_ (4) 0) the order degree of Zr_ (25) Ni_3Cu_ (12) Be_ (20) amorphous alloy increases and the creep resistance increases, while the cast amorphous alloy exhibits the worst creep resistance. The one hour anti creep resistance at 320 C can show the best amorphous state for the best.XRD results in the sample, and the TEM display sample increases with the increase of annealing temperature. As the crystallization occurs, the atomic order degree increases. In addition, the creep resistance of the sample can be changed with the increase of the loading charge. The depth of the nano indentation diamond press into the sample surface increases with the increase of the loading charge. The creep displacement increases with the load increasing in the 300s time, and the amorphous alloy in the steady creep stage. The steady-state creep rate increases with the increase of external loading. The.XRD curve of the nano indentation creep behavior of crystalline amorphous alloys shows that after different degrees of crystallization, the samples have been crystallized at different degrees. The DSC curves obtained the precise crystallization fraction.TEM diagram and the results of the electron diffraction diagram showing that the material is crystallized in the crystallization. The nano indentation creep curves show that the creep resistance of the material increases with the increase of the degree of crystallization under the same loading condition. With the same crystallization degree, the sample has strong dependence on the loading charge, the depth of the pressure head pressure in the surface increases with the increase of the loading charge, and the creep position in the steady state of the creep. The displacement increases and the steady state creep rate increases.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG139.8

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