超声波振动对Al-8.0%Cu合金抗裂性的影响

以Al-Cu合金为原材料,研究超声波对Al-8.0%Cu合金热裂倾向性的影响。结果表明,金属熔体经过超声波处理后,合金的抗裂力增大,热裂倾向明显降低,断口为沿晶断裂并且存在明显的液膜拉伸痕迹。     

半固态加热对熔体混合后铝硅合金组织的影响

通过对熔体混合后的高硅铝合金进行半固态加热处理,采用金相分析等手段对半固态加热后Al-20%Si合金组织演变规律进行研究。试验表明:半固态加热后的组织依赖于原始组织,熔体混合后得到的均匀细小的组织再进行半固态加热后容易球化。在590℃下进行5min循环加热3次可以获得细小、近球形组织。     

高能球磨时间对铝硅合金导电性能的影响

采用激光粒度分析、SEM分析等方法,研究了在高能球磨制备铝硅合金过程中随着球磨时间推移,颗粒形貌和粒径的变化,及对合金导电性能的影响。结果表明:球磨时间为12h时,铝硅合金(质量成分比为Al-20Si-0.35RE)的导电性能最佳。     

原位自生TiB2p/Al-18%Si复合材料的组织和性能

采用TiO2和KBF4粉体为反应物,适量Na3AlF6为覆盖剂,用熔体直接反应法制备了TiB2p/Al-18%Si复合材料,通过OM、SEM和EPMA对复合材料的相及微观组织进行研究,并测试了常温条件下复合材料的硬度、抗拉强度和干滑动摩擦磨损性能。结果表明,原位反应生成的TiB2颗粒尺寸小于1μm,且大多数在Al-18%Si合金基体中均匀分布,粗大的α-Al枝晶和针状共晶Si组织得到细化;复合材料的硬度、抗拉强度、摩擦磨损性能高于无TiB2颗粒的Al-18%Si合金。     

铸造铝硅合金中Ce、P双重变质作用

本文研究了Al-18.76%Si和Al-12%Si两种成分合金同时加Ce、加P后组织的变化。结果得出Ce、P联合变质可以使Al-Si合金共晶Si、初晶Si同时细化;Si相扫描电镜分析表明,Ce、P联合变质后共晶Si呈纤维状,初晶Si形态聚集规整化。Ce,P间有一定的相互抵触作用,二者的含量适当时才能获得良好的双相变质组织。     

用超声波处理过共晶铝硅合金熔体

本专利涉及一种在生产过共晶铝硅成型铸件时采用超声波方法处理金属熔体来提高它的力学性能的方法，处理工艺如下：首先对熔体进行除气，再加入含磷的变质剂进行变质处理，然后，将它进行超声波处理，使其空化现象作用整个金属液体，超声波处理的时间取决于所加入的变质剂的浓（对于金属液，一般在0．01％～0．06％），在0．15～1．2s之间，处理的目的是提高该合金在高温下的疲劳强度。     

Er对挤压态Al-Mg-Si合金低周疲劳行为的影响

为了研究Er对挤压态Al-0.8%Mg-0.6%Si合金的低周疲劳行为的影响,进行了总应变控制的室温低周疲劳实验。结果表明,低周疲劳加载条件下,挤压态Al-0.8%Mg-0.6%Si和Al-0.8%Mg-0.6%Si-0.5%Er合金主要呈现循环应变硬化现象;Er的添加可以显著提高挤压态Al-0.8%Mg-0.6%Si合金的循环变形抗力,但却降低其室温低周疲劳寿命。     

固溶处理工艺对改良铸造铝硅合金组织和性能的影响

通过不同温度和时间的固溶制度研究了固溶处理工艺对改良铸造铝硅合金(0.35%Mg,7.0%Si,0.2%Ni,2.0%Cu,0.8%RE,0.2%Mn,0.1%V,其余为铝)组织和性能的影响。实验结果表明,在495℃×5h进行固溶处理时,改良铸造铝硅合金具有最好的综合力学性能:Rm=239MPa,硬度=103HBS,A=6.24%;改良铸造铝硅合金于495℃×5h固溶淬火析出富含Si、Cu、Ni以及RE元素的Si、Al Cu、Al6Cu3Ni、Alx Cu Ce相。这些相的存在,有利于提高合金的力学性能和高温性能。合金经过热处理后以韧性断裂为主要方式并伴有准解理面现象,拉伸断口微观形貌主要表现为韧窝断口特征,有些存在少量撕裂棱。     

镁对过共晶铝铁合金组织形貌的影响

针对普通熔铸条件下过共晶Al-Fe合金初生富铁相严重割裂基体、恶化合金性能的问题,采用元素Mg对过共晶Al-5%Fe合金进行变质细化处理,Mg以Al-10%Mg中间合金形式加入。借助光学显微镜等分析了Al-10%Mg中间合金晶粒细化剂加入量和熔体保温时间对过共晶Al-5%Fe合金微观组织形貌及性能的影响。试验表明:在过共晶Al-5%Fe合金中加入Al-10%Mg中间合金细化剂,当加入量为1.2%、保温时间90min时,细化效果较好,Al-5%Fe合金中初生A13Fe相由未添加细化剂时的粗大板条状变为花朵状和颗粒状,并且尺寸明显减小,从而显著提高材料的强度和塑性。     

预变形对Al-3.7Cu-1.6Mg合金断裂韧性的影响

对固溶–淬火处理后的Al-3.7Cu-1.6Mg合金板材进行变形量分别为0、5%和10%的预拉伸处理,然后置于空气中进行自然时效,研究预变形对Al-3.7Cu-1.6Mg合金自然时效态的硬度、室温拉伸性能和断裂韧性的影响,利用扫描电镜(SEM)与透射电镜(TEM)观察合金的显微组织及断口形貌,研究其断裂机理。结果表明:该合金在淬火后引入预拉伸变形,可显著提高其自然时效态的硬度和屈服强度,同时抑制GPB区的形成,降低时效析出速率,并使峰时效时间延长;随预变形量从0增加至10%,Al-3.7Cu-1.6Mg合金的断裂韧性降低,这主要是预变形增加了基体内的位错密度,位错切割细小的GPB区粒子,大量滑移被抵消,造成变形过程中局部应力集中,从而形成微裂纹;由断口分析可知该合金的断裂类型为穿晶韧窝型断裂,且随预变形程度增大,韧窝直径和深度均增大。     

Effect of neodymium on primary silicon and mechanical properties of hypereutectic Al-15%Si alloy

The mechanical properties of hypereutectic Al-Si alloys are mainly determined by size and morphology of the primary silicon phase.So,optical microscopy(OM) and X-ray diffraction(XRD) were adopted to study affection of Nd on primary silicon of hypereutectic Al-15%Si alloy in this paper.The results of OM showed that pure Nd could effectively refine primary silicon of hypereutectic Al-15%Si alloy.When Nd addition was 0.3%,the average size of primary silicon reduced from 20-40 μm of initial sample to 10-20 μm of modified sample.XRD pattern showed that no new phase was formed after Nd modification.The results of mechanical properties test showed that whole properties of modified samples were significantly improved.Tensile strength increased about 32.6% from 147 MPa to 195 MPa.Elongation was increased about 160% from 1.0% to 2.6%.The improvement of mechanical properties should attribute to primary silicon refinement after modification.     

Effect of neodymium on primary silicon and mechanical properties of hypereutectic Al-15%Si alloy

The mechanical properties of hypereutectic Al-Si alloys are mainly determined by size and morphology of the primary silicon phase. So, optical microscopy (OM) and X-ray diffraction (XRD) were adopted to study affection of Nd on primary silicon of hypereutectic Al-15%Si alloy in this paper. The results of OM showed that pure Nd could effectively refine primary silicon of hypereutectic Al-15%Si alloy. When Nd addition was 0.3%, the average size of primary silicon reduced from 20-40 μm of initial sample to 10-20 μm of modified sample. XRD pattern showed that no new phase was formed after Nd modification. The results of mechanical properties test showed that whole properties of modified samples were significantly improved. Tensile strength increased about 32.6% from 147 MPa to 195 MPa. Elongation was increased about 160% from 1.0% to 2.6%. The improvement of mechanical properties should attribute to primary silicon refinement after modification.     

高能球磨制备高铝锌铝合金粉末的研究

首先采用一步球磨法制备了成分为Zn-30Al-6Si-0.5Cu(质量分数/%)和Zn-30Al-3Si-3Cu(质量分数/%)的高铝锌铝合金粉末,其次采用二步球磨法制备了成分为Zn-30Al-6Si-0.5Cu(质量分数/%)的合金粉末,并利用XRD、SEM粒度分析仪对粉末的物相组成、颗粒形貌及粒度进行了表征和分析。结果表明:含硅量为6%的合金粉末的颗粒尺寸比含硅量为3%的合金粉末更为细小,尺寸分布更为集中,球磨12h之后的粉末其金相组织主要由富Al的α相、富Zn的η相以及Si相组成。经过二步球磨后的Zn-30Al-6Si-0.5Cu粉末中Al9Si相基本消失,Si相含量增加;二步球磨法制备的粉末颗粒尺寸更为细小。通过扫描电镜观察发现粉末形貌不规则,且分布不够均匀,粉末中基本未观察到类似焊片的颗粒。     

Al-3B变质对铸造Al-10Si合金显微组织与力学性能的影响

采用Al-3B对铸造Al-10Si合金进行了变质处理,运用非平衡相图和杠杆定律分析了变质处理Al-10Si合金显微组织变化规律,研究了变质处理对合金力学性能的影响.研究表明,Al-3B变质处理使铸造Al-10Si合金的凝固过冷度减小;当变质温度一定时,随着Al-3B加入量增加,铸造Al-10Si合金组织中初生α-Al相...     

Influence of treatment of melts by electromagnetic acoustic fields on the structure and properties of alloys of the Al–Si system

The influence of treating the melts by electromagnetic acoustic fields on the structure and properties of Al–12% Si and Al–20% Si binary alloys is investigated. In the course of experiments, the frequency of the electromagnetic field induced in the loop antenna varies as 500, 1000, and 2000 kHz. The melts are treated after their degassing and refining. It is established that this treatment method of the melts leads to a reduction of the total preparation time of alloy by 12% on average. The short-term treatment of the melts by electromagnetic acoustic fields promotes the refinement of the main phase components of alloys and an increase in their mechanical properties. When treating the Al–12% Si eutectic alloy with a frequency of 500 kHz, α-Al dendrites are refined from 30 to 22 μm and eutectic Si crystals are refined from 13 to 10 μm. When treating the Al–20%Si eutectic alloy with a frequency of 1000 kHz, eutectic Si crystals diminished from 8 to 5 μm and these of primary Si diminished from 90 to 62 μm. The ultimate tensile strength of the Al–12%Si eutectic alloy increases 13% under the mentioned treatment modes, while the relative elongation increases 17%; as for the Al–20% Si eutectic alloy, the same characteristics increases 9 and 65%, respectively. Based on these investigations, it is concluded that the selection of the treatment parameters of the melts of the Al–Si system by electromagnetic acoustic fields should be determined by the silicon content in the alloy. It is necessary to treat the melt by waves with a higher oscillation frequency with an increase in the silicon concentration. This treatment method makes it possible to form the modified fine-crystalline structure of alloy and, consequently, improves their mechanical properties. It can be successfully used when fabricating fine-crystalline foundry alloys and in the production of alloys of the Al–Si system. To determine the optimal treatment parameters depending on the structure of the initial charge and alloy nature, additional investigations are required.     

混合稀土变质高硅铝活塞合金

采用镧铈钇型混合稀土对过共晶Al—24％Si活塞合金进行了变质处理,对其金相组织和力学性能进行了研究。结果表明：与单一稀土铈变质相比较,镧铈钇型混合稀土对该合金具有较好的变质效果,初晶硅的尺寸基本保持在20μm左右,且尖角大多钝化呈团球化状,共晶硅呈短杆状均匀分布;合金经过混合稀土变质后,晶界处产生复杂化合物组织起到了弥散强化作用,使其综合力学性能明显提高,尤其是高温强度的显著提高,已完全满足活塞合金在使用性能上对高温强度的要求。     

Influences of different Zr/Sc ratios on microstructure and mechanical properties of Al-2Si alloy

The influences of different Zr/Sc ratios on the microstructural evolution and mechanical performances of Al-2 Si alloy were investigated in this paper.The as-cast samples were characterized and analyzed by the scanning electron microscope(SEM) with an energy dispersive spectrometer(EDS) to indicate the refining effect of the different Zr/Sc ratios on the α-Al and Si phases in Al-2 Si alloy.The results indicate that the α-Al phases are refined from coarse dendritic structure to relatively fine equiaxed grains when the Zr/Sc ratio is equal to 1:1.Meanwhile,the eutectic Si phase in Al-2 Si-0.2 Zr-0.2 Sc alloy is modified from the coarse plate and needle to fine fiber and partial granular structure,and the average roundness of eutectic Si is decreased by 75% from 16 to 4.With the refinement of α-Al phases and the modification of eutectic Si structure,the ultimate tensile strength(UTS) is improved by 53% and the elongation(EL) is increased by 64% when the Zr/Sc ratio is equal to 1:1.In addition,the UTS decreases and EL is enhanced with the increase of tensile temperature.Moreover,the fracture model of Al-2 Si-0.2 Zr-0.2 Sc alloy in250℃ changes into the ductile fracture.     

复合变质对过共晶Al-24％Si合金组织的影响

对过共晶Al-24％Si合金进行了单一磷、稀土及磷和稀土双重复合变质处理。实验表明,磷和稀土双重复合变质能够有效的细化合金的组织,变质后合金中的初晶硅晶粒平均尺寸由变质前的60μm变为20μm,且分布均匀．共晶硅也由长针状变为短杆状。同时对磷和稀土的双重复合变质机理做了初步探讨。