锆基非晶合金微观结构与力学性能的研究

发布时间：2018-05-01 06:14

本文选题：块体非晶合金 + 力学性能　；参考：《兰州理工大学》2017年硕士论文

【摘要】：由于锆基非晶合金优异的力学性能和不同于晶态金属材料的结构,人们对它的研究兴趣愈来愈浓厚。但是锆基块体金属玻璃作为结构材料在具有诸多优异性能的同时也存在一些问题,比如脆性断裂问题,非晶合金具有塑性时的结构问题,以及非晶合金制备时外部条件对其性能影响的问题等都是目前非晶合金急需解决的。本文延续课题组前期的研究工作,通过对(Zr_(0.761)Cu_(0.147)Ni_(0.092))92-x Al8+x、(Zr_(0.72)Cu_(0.278)Ag_(0.002))_(88)Al_(12)、(Zr_(0.72)Cu_(0.165)Ni_(0.115))88Al12等锆基块体非晶合金采用X射线衍射,差热分析,室温压缩实验和显微硬度测试等方式对它们的力学性能和微观结构进行测试分析,得到以下结果:(1)通过对(Zr_(0.761)Cu_(0.147)Ni_(0.092))92-x Al8+x非晶合金Al元素的调整,得到了大尺寸的具有较好塑性的(Zr_(0.761)Cu_(0.147)Ni_(0.092))_(92)Al_(10)非晶合金。合金直径3mm试样塑性变形εp达到了15.82%,且此成分具有较好的非晶成形能力,过冷液相区ΔTx达到了94K;并且随着Al含量的增加,(Zr_(0.761)Cu_(0.147)Ni_(0.092))92-x Al8+x合金的屈服强度和显微硬度都有所增加,且当x=6时达到最大的1713MPa和4096MPa。(2)通过对(Zr_(0.761)Cu_(0.147)Ni_(0.092))92-x Al8+x非晶合金混合焓ΔH_(mix)和混合熵ΔS_(mix)的计算,发现当ε越接近1,合金的热稳定性越好;通过对合金塑性变形时产生的锯齿流变行为进行统计分析发现,随着塑性应变的持续,合金锯齿流变中应力降幅Δσs波动越稳定,则合金塑性越好,反之当合金应力降幅波动越来越大,则合金越容易失稳,塑性越小;通过对腐蚀后的(Zr_(0.761)Cu_(0.147)Ni_(0.092))92-x Al8+x非晶合金试样进行显微硬度测试,发现硬度在合金软硬区的显微硬度不同,且两者硬度差值越大,则合金塑性越好。(3)通过快速凝固,得到不同冷却速率下的(Zr_(0.72)Cu_(0.278)Ag_(0.002))_(88)Al_(12)合金试样,通过对试样进行室温压缩实验。发现,随着冷却速率的下降,合金的塑性明显降低,在6mm时发生脆断,与之相反的是,非晶合金的强度却显著增大(6mm试样晶化,较大的晶粒使其强度显著降低)。通过对塑性较好2mm试样进行腐蚀并结合背散射电子分析发现,腐蚀表面出现了类似网状结构。通过分析发现,网的产生是由于合金被腐蚀掉的结构相较于基体更易腐蚀,结构更加“松散”,也就是非晶合金中微观结构不均匀。而通过对具有较好塑性的(Zr_(0.72)Cu_(0.165)Ni_(0.115))88Al12非晶合金3mm试样进行纳米压痕测试,这一猜测得到证实。(4)通过对铸态(Zr_(0.72)Cu_(0.278)Ag_(0.002))_(88)Al_(12)块体非晶合金直径2mm和3mm试样进行等温退火处理,经室温压缩实验和显微硬度测试。结果表明,随着退火时间的延长,合金2mm试样塑性逐渐变差,而强度逐渐增大;但3mm试样塑性和强度却均是先减小后增大。而合金的显微硬度不论2mm试样还是3mm试样都随着退火时间的延长而增大,而且两者之间呈线性关系。
[Abstract]:Because of the excellent mechanical properties and structure of zirconium based amorphous alloys, people are more and more interested in the research of zirconium based amorphous alloys. However, as a structural material, zirconium based bulk metallic glass has many excellent properties, such as brittle fracture, structural problems when amorphous alloy is plastic. The problems of the influence of external conditions on the properties of amorphous alloys are urgently needed to be solved. This paper continues the previous research work of the research group. By using X-ray diffraction, differential thermal analysis (DTA) is used to analyze Zr-based bulk amorphous alloys, such as 0.147NII Al8 0.272 Al8, 0.272 Al8, 0.278Ag-DTA, 0.278Agtix, 0.278Ag-DX, 0.278Ag-DTA, DTA, DTA, DTA, DTA, DTA, DTA, DTA, DTA, DTA, DTA, DTA, DTA, DTA, DTA, DTA, DTA, DTA, DTA, DTA, DTA, DTA, DTA, DTA, DTA, DTA, DTA, DTA, DTA, DTA, DTA, DTA, DTA The mechanical properties and microstructure of these alloys were tested and analyzed by means of room temperature compression test and microhardness test. The following results were obtained: 1) the adjustment of Al elements in amorphous alloy 92-x Al8 x was carried out by adjusting the Al element of the amorphous alloy. A large-size amorphous alloy with a good plasticity of 0.761Cu+ / 0.147N / Nitig / 0.092 / T / T / 92AlC10) has been obtained. The plastic deformation 蔚 p of alloy diameter 3mm specimen has reached 15.82, and this component has better amorphous forming ability, 螖 Tx in undercooled liquid phase reaches 94 K, and the yield strength and microhardness of Al8 x alloy increase with the increase of Al content. When x = 6 reaches the maximum 1713MPa and 4096MPa.f2) through the calculation of the mixture enthalpy 螖 H mixed and the mixed entropy 螖 S / S mixture of the 1713MPa and 4096 MPa.f2), it is found that the thermal stability of the alloy is better when 蔚 is closer to 1. The results show that the heat stability of the alloy is better when 蔚 is closer to 1, and the mixture enthalpy of the amorphous alloy is calculated by means of the calculation of the mixture enthalpy 螖 H ~ (+) and the mixed entropy 螖 S / S _ (+) of the amorphous alloy. Through the statistical analysis of the rheological behavior of the sawtooth during plastic deformation, it is found that the more stable the fluctuation of stress 螖蟽 s in the rheology of the alloy is, the better the plasticity of the alloy is. On the contrary, when the stress fluctuation of the alloy is more and more large, the instability of the alloy is more easily and the plasticity of the alloy is smaller. By testing the microhardness of the corroded sample of Nijiu 0.092x Al8 x amorphous alloy, it is found that the hardness of the amorphous alloy is different in the soft and hard region of the alloy, and the hardness is different in the hard and soft region of the alloy. Moreover, the greater the hardness difference between them, the better the alloy plasticity. It is found that with the decrease of cooling rate, the plasticity of the alloy decreases obviously, and brittle fracture occurs at 6mm. On the contrary, the strength of the amorphous alloy increases significantly with the crystallization of the 6mm sample, and the strength of the amorphous alloy decreases significantly with the larger grain size. It is found that the corrosion surface of the 2mm specimen with good plasticity is similar to that of the network structure by means of backscatter electron analysis. Through analysis, it is found that the structure of the alloy corroded is more easily corroded than the matrix, and the structure is more "loose", so the microstructure of the amorphous alloy is not uniform. The nanoindentation tests on the 3mm specimens of the amorphous alloy 3mm with better plasticity were carried out. The results show that the as-cast SnZR 0.272 CuV 0.278Ag0.002Ag-0.002Ag-888 Aln12) bulk amorphous alloy diameter 2mm and 3mm samples are annealed by isothermal annealing, and the results are as follows: (1) in this paper, the results are as follows: (1) the as-cast bulk amorphous alloy 2mm and 3mm samples are annealed by isothermal annealing, and the results show that the as-cast amorphous alloy 2mm and 3mm samples are annealed by isothermal annealing. At room temperature compression test and microhardness test. The results show that with the increase of annealing time, the plasticity and strength of 2mm alloy become worse and the strength increases gradually, but the plasticity and strength of 3mm specimen decrease first and then increase. The microhardness of both 2mm and 3mm alloys increases with the increase of annealing time, and there is a linear relationship between them.
【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG139.8

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