一种Zr基非晶合金在过冷液相区的本构关系研究

发布时间：2018-03-07 19:10

本文选题：非晶合金　切入点：过冷液相区　出处：《沈阳工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：非晶合金具有优良的综合性能,非晶合金在过冷液相区内表现出超塑性,适于非晶合金的成形。本文所选用的(Zr33.2Ti36.1Ni5.8Be24.9)91Cu9非晶合金具有较大的非晶形成能力,通过铜模铸造制备了长度为80mm,宽度为12mm,厚度为2mm的(Zr33.2Ti36.1Ni5.8Be24.9)91Cu9非晶合金板材。采用X射线衍射(XRD)和差示扫描量热仪(DSC)对所制备的样品进行结构分析和热差分析。采用在MTS Exceed万能力学性能试验机在(Zr33.2Ti36.1Ni5.8Be24.9)91Cu9非晶合金过冷液相区内,温度范围为612K~632K,应变速率范围为1.0×10-3s-1~0.1×10-3s-1,进行拉伸实验,并通过扫描电镜(SEM)进行对断口形貌进行观察。获得的主要研究结果如下:通过XRD铸态(Zr33.2Ti36.1Ni5.8Be24.9)91Cu9合金结构为非晶态,通过DSC确定了非晶合金的玻璃转变温度Tg=612K,晶化开始温度Tx=671K,过冷液相区?T=Tx-Tg=59K当温度低于617K或者是应变速率高于0.75×10-3s-1的时,(Zr33.2Ti36.1Ni5.8Be24.9)91Cu9非晶合金发生应力过冲现象。而随着应变的增加,由应力过冲的非牛顿流动变形转变为牛顿流动变形。当温度高于622K或应变速率低于0.5×10-3s-1时,(Zr33.2Ti36.1Ni5.8Be24.9)91Cu9非晶合金表现为不发生应力过冲的牛顿流变形式。在牛顿流变过程中,断口呈现出大量放射状脉络花纹和少量的熔融状液滴。随着应变速率的升高和温度的降低,(Zr33.2Ti36.1Ni5.8Be24.9)91Cu9非晶合金的断口由放射状脉络花纹逐渐转变为羽项型花纹或者是叶脉状花纹,此非晶合金由韧性断裂转变为脆性断裂。采用扩展指数模型、自由体积模型、Maxwell-Pulse模型对(Zr33.2Ti36.1Ni5.8Be24.9)91Cu9非晶合金在拉伸实验条件下进行拟合:自由体积方程能够表征(Zr33.2Ti36.1Ni5.8Be24.9)91Cu9非晶合金在拉伸实验条件下的应力过冲现象和稳态流动变形,对某一特定区域拟合曲线与实验数据存在差异较大;扩展指数方程能够表征(Zr33.2Ti36.1Ni5.8Be24.9)91Cu9非晶合金在拉伸实验条件下的稳态流动变形,不能拟合出最大应力过冲值,使用范围局限;Maxwell-Pulse本构方程能够很好的表征(Zr33.2Ti36.1Ni5.8Be24.9)91Cu9非晶合金在拉伸实验条件下的稳态流动变形和应力过冲现象。
[Abstract]:The amorphous alloy has excellent comprehensive properties, and the amorphous alloy exhibits superplasticity in the supercooled liquid region, which is suitable for the forming of the amorphous alloy. The amorphous alloy selected in this paper has a large amorphous forming ability, which is composed of 33.2 Ti36.1Ni5.8Be24.9Ni5.8Be24.9Cu9 amorphous alloys. Amorphous Zr33.2Ti36.1Ni5.8Be24.9Cu9 alloy plates with length of 80mm, width of 12mm and thickness of 2mm were prepared by copper mold casting. The structure and thermal difference of the samples were analyzed by X-ray diffraction (XRD) and differential scanning calorimeter (DSC). Exceed universal mechanical property tester was used in the supercooled liquid phase region of Zr33.2Ti36.1Ni5.8Be24.9B91Cu9 amorphous alloy. The tensile test was carried out and the fracture morphology was observed by SEM (scanning electron microscope). The main results obtained were as follows: the amorphous structure of Zr33.2Ti36.1Ni5.8Be24.91Cu9 alloy was obtained by the XRD cast state of Zr33.2Ti36.1Ni5.8Be24.91Cu9 alloy. The glass transition temperature (TG) of amorphous alloy was determined by DSC, the crystallization start temperature was T _ (x) 671 K, and the supercooled liquid phase region was obtained. When the temperature is below 617K or the strain rate is higher than 0.75 脳 10 ~ (-3) s ~ (-1), the stress overshoot occurs in the amorphous alloy Zr33.2Ti36.1Ni5.8Be24.9 / 91Cu9. When the temperature is higher than 622K or the strain rate is lower than 0.5 脳 10 ~ (-3) s ~ (-1), the Zr33.2Ti36.1Ni5.8Be24.9Cu _ 9 amorphous alloy exhibits a Newtonian rheology without stress overshoot. With the increase of strain rate and the decrease of temperature, the fracture surface of Zr33.2Ti36.1Ni5.8Be24.9 91Cu9 amorphous alloy gradually changed from radial choroid pattern to plume pattern or leaf vein pattern. The amorphous alloy changed from ductile fracture to brittle fracture. The free volume model and Maxwell-Pulse model were used to simulate the tensile test of Zr33.2Ti36.1Ni5.8Be24.9N 91Cu9 amorphous alloy. The free volume equation can characterize the stress overshoot and steady flow deformation of Zr33.2Ti36.1Ni5.8Be24.924.91Cu9 amorphous alloy. There is a great difference between the fitting curve and the experimental data for a particular region, and the extended exponential equation can characterize the steady flow deformation of Zr33.2Ti36.1Ni5.8Be24.9CU _ 9 amorphous alloy under tensile test conditions, and can not fit the maximum stress overshoot value. The Maxwell-Pulse constitutive equation can be used to characterize the steady flow deformation and stress overshoot of Zr33.2Ti36.1Ni5.8Be24.9Cu9 amorphous alloy under tensile test conditions.
【学位授予单位】：沈阳工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG139.8

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