【作者】 马海健；

【导师】 王伟民；

【作者基本信息】 山东大学 ， 材料加工工程， 2011， 博士

【摘要】 本文选择铁基非晶为研究对象,分别研究了Ni、Zr、Y等不同类别元素的添加对铁基非晶非晶形成能力、热膨胀行为、力学性能、磁学性能、耐腐蚀性能等的影响。此外,还研究了Ni和Y元素的添加对铁基非晶等温退火及快淬过程中初晶析出相的结构、晶化析出机理、软磁性能等的影响。利用X射线衍射仪(XRD)、差示扫描量热仪(DSC)、振动样品磁强计(VSM)和电化学工作站分析了铁磁性元素Ni添加对Fe78Si9B13非晶合金非晶形成能力、磁学性能和耐腐蚀性能的影响。研究表明,Ni的添加降低了Fe78Si9B13非晶合金的非晶形成能力和软磁性能。分析认为,Ni的添加(1)使Fe-Si-B-Ni合金由共晶点向过共晶点偏离；(2)使Fe-Si区中的Si原子偏离Fe-Si区,从而促进了初晶α-Fe相的形成,降低了合金的非晶形成能力。Ni的添加提高了(Fe0.78Si0.09B0.13)100-xNix (x=0,2,3和5)非晶合金在酸性、盐及碱性溶液中的耐腐蚀性能。合金钝化保护能力的提高是由于Ni的添加促进了Si原子向合金表面的扩散,在合金表面形成了稳定且连续的Si氧化物保护膜的缘故。利用XRD、透射电子显微镜(TEM)、显微硬度仪分析测试了Ni的添加对(Fe0.78Si0.09B0.i3)100-xNix(x=0,2和5)非晶合金等温退火过程中的初晶析出相的结构和析出机理的影响,以及(Fe0.78Si0.09B0.13)95Nis合金不同快淬条件下力学性能的变化。结果显示,Fe-Si-B-Ni合金在快淬和等温退火晶化过程中的初晶析出相都是α-Fe(Si)固溶体；在等温退火过程中,Ni的添加促进了初晶a-Fe的形核,抑制了残余非晶基体的进一步分解。在(Fe0.78Si0.09B0.13)100-xNix(x=0,2和5)非晶合金的晶化过程中,初晶相α-Fe的晶格常数和晶粒尺寸随退火时间的延长出现背离现象。这与α-Fe生长过程中结晶前沿Si的浓度随α-Fe晶粒的长大而升高有关。经快淬(Fe0.78Si0.09B0.13)95Ni5合金所获得的非晶和部分非晶条带以及相应的条带的辊面和自由面的显微硬度值存在差异。条带辊面的显微硬度值要高于自由表面的硬度值；部分非晶条带的辊面和自由表面的显微硬度值都要高于相应的非晶条带的硬度值。使用的制备设备以及不同的快淬条件所引起的析出相强化和晶界强化是造成这种差异的原因。利用XRD、DSC、热膨胀仪(DIL)、VSM分析测试了前过渡族大原子元素Zr的添加对(Fe0.78Si0.09B0.13)100-xrZrx(x=0,1,2)合金非晶形成能力、热膨胀性能和磁学性能的影响。结果表明适量Zr的添加(1 at.%)可提高合金的非晶形成能力,但进一步增加Zr的含量则恶化了合金的非晶形成能力。这是由于适量Zr的添加使Zr与B原子在非晶合金中形成了骨架增强型结构,稳定了合金的过冷熔体,抑制了初晶相的析出,提高了合金的非晶形成能力。另外,Fe-Si-B-Zr非晶合金热膨胀系数曲线与其DSC曲线具有对应关系,说明该合金的收缩阶段主要是由合金的晶化所引起的。热磁曲线M-T上的居里转变温度Tc与DSC曲线和DIL曲线上的居里转变温度符合的很好,表明铁基非晶的居里转变可由此三种测试方式来表征。利用XRD、DSC、TEM测试分析了稀土元素Y的添加对工业级原材料Fe79.77M0.23B20(M为杂质元素)合金非晶形成能力的影响。研究表明,添加Y能提高合金的非晶形成能力。Y的添加可以净化合金熔体,改善合金中原子之间的错配度,增强合金过冷熔体的稳定性,抑制晶体相的析出,进而提高了合金的非晶形成能力。利用XRD、TEM、VSM分析测试了Fe71.51M0.49Y6B22 (M为杂质元素)非晶合金等温退火过程中磁学性能的变化。结果显示,饱和磁化强度Ms和矫顽力Hc随退火时间的延长呈背离趋势。这是由于在等温退火过程中,大原子Y和小原子B会被初晶α-Fe排斥出去,在α-Fe周围的残余非晶基体上分别形成不同的浓度梯度,引起初晶α-Fe晶粒的细化,导致饱和磁化强度Ms和矫顽力Hc出现背离现象。利用扫描电子显微镜(SEM)和电化学工作站对Fe75.77M0.23Y4B20和Fe71.51M0.49Y6B22(M为杂质元素)非晶合金的耐腐蚀性能进行了分析测试。结果显示,在酸性、盐溶液中,Fe75.77M0.23Y4B20非晶合金的耐腐蚀性能要好于Fe71.51M0.49Y6B22合金。分析认为,大原子元素Y的添加会使(FeM)-Y-B (M为杂质元素)非晶合金最近邻原子距离发生改变,导致合金内部应力及自由能态发生变化,进而使合金表面原子的电化学活化能及表面活性原子数量发生改变,影响了铁基非晶合金的耐腐蚀性能。更多还原

【Abstract】 In the present thesis, the effect of Ni, Zr and Y on the glass forming ability (GFA), thermal expansion behavior, mechanical properties, magnetic properties and corrosion resistance of the Fe-based glassy alloys have been investigated. In addition, the influence of Ni and Y on the primary crystalline phases, precipitation mechanism, and soft magnetic properties in isothermal annealing and rapid solidification process of Fe-based glass alloys have been discussed as well.The influence of Ni on the GFA, magnetic properties and corrosion resistace of Fe78Si9Bi3 glassy alloys were investigated by X-ray diffraction (XRD), differential scanning calorimetry (DSC), vibrating sample magnetometer (VSM), electrochemical workstation and scanning electron microscopy (SEM). The results show that the addtion of Ni decreases the GFA and soft magnetic properties of Fe78Si9B13 glassy alloys. The additon of Ni can induce:(1) the deviation of Fe-Si-B-Ni from eutectic point into the hypereutetic regime; (2) the deviation of Si atoms from Fe-Si region which promotes the nucleation of primaryα-Fe phase. The addition of Ni enhances the corrosion resistance of (Fe0.78Si0.09B0.13)100-x.Nix(x= 0,2,3,5) glassy alloys. The improvements of the passive protective properties attribute to the addition of Ni which can promote the diffusive of the Si atoms to the surface of the alloys, and subseqently the Si atoms form a stable and continouos protective SiO2 film.The influence of Ni on the structure and primary crystalline precipitation mechanism of (Fe0.78Si0.09B0.i3)100-x-Nix (x= 0,2,5) glassy alloys, and the mechanical properties of the (Fe0.78Si0.09B0.13)95Ni5 alloy after rapid solidification have been investigated by XRD, transimission electron microscopy (TEM) and microhardness tester. The resuls show that the primary crystalline phases of Fe-Si-B-Ni glassy alloys are a-Fe(Si) solid solution in the rapid solidfication and isothermal annealing process. In the isothermal annealing process, the addition of Ni promotes the nucleation of primary crystalline a-Fe phase, inhabites the decompositon of residual glassy matrix. As the annealing time increases, the lattice constant and grain size of the primary phase show an opposite trend in the crystallization process. The results are related to that the concentration of Si atoms increases in the crystallization interface as the primary a-Fe phase grows up. The microhardness values (H、) between the wheel side and the free side are different, both in glassy and partial crystalline ribbons of the as-cast (Fe0.78Si0.09B0.13)95Ni5 alloy ribbons. The H、of the wheel side is larger than that of the free side, and the glassy ribbon is smaller than that of the partial crystalline ribbon both in the wheel side and the free side. It is ascribed to precipitation and grain boundary strengthening which caused by the fabricating equipment and the different spinning conditions.The effect of Zr on the GFA, thermal expansion properties and magnetic properties of (Fe0.78Si0.09B0.13)100-xZrx(x=0,1,2) alloys were investigated by XRD, DSC, dilatometer (DIL) and VSM. The results show that appropriate Zr addition (1 at. %) can improve the GFA and thermal stability of the Fe-Si-B-Zr alloys. However, further increase of Zr addition deteriorates the GFA. Appropriate addition of Zr can form a reinfoced backbone structure with B atoms, and this kind of structure enhances the stability of the undercooled melt, suppresses primary crystallization, all these induce the improvement of GFA. The thermal expansion coefficient curves and the DSC curves have a similar trend, suggesting that the contraction process on the DIL curve is mainly ascribed to the crystallization process of the Fe-based glassy alloys. The Curie transition temperature T。on the temperature-magnetization(M-T) curves is agree well with the Curie transition temperature on the DSC and DIL curves, implying that the Curie transition temperature can be characterized by M-T, DSC and DIL method.The effect of Y on the GFA of the commercial Fe79.77M0.23B20 (M= impurity elements) alloy were investigated by XRD, DSC, TEM. The results show that Y can improve the GFA. It is attributable to that Y has a scavenging effect on the alloy melt, which can improve the stability of undercooled melt and suppress the cyatallization. The variety of the soft magnetic properties of the Fe71.51M0.49Y6B22 (M= impurity elements) in the isothermal annealing process was investigated. With the annealing time extending, the saturation magnetization Ms presents an opposite to the trend coercivity Hc. In the isothermal annealing process, the large atom Y and the small atom B will be rejected by primary crystalline a-Fe phase, and form a different concentrantion gradient around the a-Fe in the residual amorphous matrix. It promotes to the refine of a-Fe grain as well as result in the opposite trend between Ms and Hc.The corrosion resistance of the Fe75.77M0.23Y4B20 and Fe71.51M0.49Y6B22(M impurity elements) glass alloys were investigated by electrochemical workstation and SEM. The results show that the corrosion resistance properties of Fe75.77M0.23Y4B20 glass alloy is better than that of Fe71.51M0.49Y6B22. The addition of large atom Y can change the nearest neighbor distance of the (FeM)-Y-B (M= impurity elements) alloys, and result in the change of the free energy level and the internal stress of the alloy. Furthermore, it changes the electrochemical activation energy of the alloys and the amount of activated atoms on the surface. All these result in the variation of corrosion resistance of the glassy alloys.更多还原