添加Mo元素对Fe40Co40Zr9B10Ge1合金晶化过程和磁性能影响

采用单辊快淬法制备Fe40Co40Zr9B10Ge1和Fe40Co40Zr5Mo4B10Ge1两种非晶合金,并在不同温度下对其进行热处理。利用XRD和VSM两种仪器对合金的微观结构和磁性能进行测试分析,研究Mo添加对Fe40Co40Zr9B10Ge1合金晶化过程和磁性能的影响。结果表明,两种合金在晶化初期均有α-Fe(Co)相从非晶基体析出,但高温热处理后的晶化产物不同,Mo添加减少了高温金属化合物的含量。低于675℃热处理,Mo添加降低了合金晶化过程中析出α-Fe(Co)相的晶粒尺寸和合金的矫顽力。     

M(o)ssbauer and electron microscopy study of martensitic transformations in an Fe-Mn-Mo alloy

The kinetic,morphological,crystallographic,and magnetic characteristics of thermally induced martensites in Fe-13.4wt%Mn-5.2wt% Mo alloy were investigated by scanning electron microscopy(SEM),transmission electron microscopy(TEM),and M(o)ssbauer spectroscopy.The experimental results reveal that two types of thermal-induced martensites,ε(hcp)and αˊ(bcc)martensites,are formed in the as-quenched condition,and these transformations have athermal characters.Mo addition to the Fe-Mn alloy does not change the coexistence of ε and αˊ martensites with the Mn content between 10wt% and 15wt%.Besides,M(o)ssbauer spectra reveal a paramagnetic character with a singlet for the γ(fcc)austenite and ε martensite phases and a ferromagnetic character with a broad sextet for the αˊ martensite phase.The volume fraction of αˊmartensite forming in the quenched alloy is much more than that of the ε martensite.     

Effect of N on microstructure and mechanical properties of as-cast Ti-6Al alloy

Duetotheirhighspecificstrength,goodcorrosionresistance,goodhightemperatureproperties,titanium andtitaniumalloysareconsideredidealmaterialsforspace,oil,chemicalandmedicalindustries[1-3].They alsohavepotentialapplicationintheautomobileindus try[4-7].Titaniu…     

Refinement role of electromagnetic stirring and calcium in AZ91 magnesium alloy

Effects of calcium addition and electromagnetic stirring on the microstructure of AZ91 magnesium alloy and refinement mechanism were investigated. The results show that calcium addition ranging from 0.1wt% to 0.3 wt% does not lead to formation of any new phases but cause the refinement of ascast microstructure.However, combined calcium alloying and electromagnetic stirring significantly decrease the grain size, change the morphologies of the β-Mg17Al12 phases,and reduce their volume percentage. The minimum grain size of AZ91 alloy is obtained in the case of the addition of 0.2 wt%Ca with exciting voltage of 100 V. The microstructural refinement is attributed to the increase of the degree of undercooling and nucleation temperature of primary α-Mg phases on the basis of DTA analysis results.     

Ti40合金吸放氢后的组织演变规律

利用XRD、OM、TEM等方法研究了Ti40合金吸氢与放氢后的组织演变规律。研究表明：由于氢在β相中的溶解度很高,Ti4合金中并没有发现氢化物的析出,但β晶界处更加宽化;当氢含量较高时,β相内开始析出α相,并伴随着硅化物粒子的析出;吸氢Ti40合金放氢后,合金中的相与原始合金一致。     

Effects of Ag on microstructure and mechanical properties of 2519 aluminum alloy

The effects of Ag on the microstructure and mechanical properties of 2519 aluminum alloy were investigated by means of tensile test, micro-hardness test, transmission electron microscope and scanning electron microscope. The results show that the addition of 0.3 % （mass fraction） Ag accelerates 2519 aluminum alloy＇s age-hardening, increases its peak hardness and reduces 4 h of peak aged time at 180 ℃. The addition of 0. 3% （mass fraction） Ag increses the tensile strength at room temperature and elevated temperature. This increment at room temperature and 200 ℃ is 24 MPa and 78 MPa, respectively. In contrast, the elongation of 2519 aluminum alloy is decreased with Ag addition. The increase of tensile strength of 2519 aluminum alloy with Ag addition is attributed to the high volume fraction of Ω phase.     

Ca对Mg-Zn合金热裂敏感性的影响

为了研究Ca元素对Mg-Zn二元合金热裂敏感性的影响,采用自制的“T”字形热裂仪器,以Mg-1.5Zn合金为基础合金,通过添加1%~4%的Ca元素来研究Mg-Zn-Ca系合金的热裂行为.采用金相显微镜及扫描电镜观察热裂区域的显微组织,分析Mg-Zn-Ca三元合金的热裂形成机理.结果表明,对于Mg-1.5Zn-xCa合金而言,随着Ca添加量的增加,热裂纹体积不断减小,合金的热裂敏感性降低; 热裂发生时,Mg-1.5Zn-xCa合金中剩余液相体积分数逐渐增加,补缩效果不断提高,热裂敏感性随着Ca添加量的增加而逐渐降低; 对于Mg-Zn-Ca合金而言,裂纹处的补缩物质为α-Mg和Ca₂Mg₆Zn₃、Mg₂Ca相的混合物.     

High temperature scaling of Ni-15Cu-5Al alloy in 1 × 105 Pa pure oxygen

The oxidation of the ternary alloy Ni-15Cu-5Al in 1 × 105 Pa pure oxygen at 700 ℃ and 800 ℃ was studied. The results show that the behavior of the Ni-rich alloy is similar to that of the binary Ni-Al alloy with the same Al content in the form of an external NiO layer coupled to the internal oxidation of aluminium. The presence of 15%(mole fraction) Cu cannot modify substantially the values of relevant parameters affecting the transition from the internal to the external oxidation of aluminium. The presence of 5 % Al reduces the oxidation rate of the corresponding Ni-Cu alloy during the whole oxidation stages, though 5 % Al is still insufficient to form protective external alumina scales.     

脉冲磁场处理非晶合金产生的纳米晶化相的磁伸性质

低频脉冲磁场处理工艺,使非晶薄带Fe78Si9B13产生纳米晶化,析出α-Fe(Si)纳米相,形成α-Fe(Si)纳米晶与剩余非晶的双相纳米合金。穆斯堡尔谱分析,随着脉冲磁场的强度提高,双相纳米晶合金的晶化相体积分数增加。纳米晶化相α-Fe(Si)的磁致伸缩系数λcs为-1.287×10-4～-1.345×10-4。控制晶化相体积分数,可以使双相纳米晶合金的有效磁致伸缩系数λes最小,有利于提高双相纳米晶合金的软磁性能。     

Cu-Zn-Al合金两相区淬火对形状记忆效应的影响

在α+β两相区不同温度淬火对CU—25.44Zn—3.94Al形状记忆合金的相组成、相变温变及形状记忆效应的影响。研究结果表明,Cu—Zn—Al合金在α+β两相区合适的温变加热淬火,晶粒细小,其形状记忆效应优于在β单相区加热淬火者且相变温度较易调整,单向和双向记忆效应最佳的淬火温变分别为720℃和700℃,讨论了α+β两相区淬火对双向记忆效应影响的机制。     

Solidification structures of high niobium containing TiAl alloys

To understand the effect of alloy stoichiometry on the microstructural development and mechanical behavior of γ-TiAlbased materials, it is necessary to have a determination of the phase relationships for the TiAl alloy system near the γ phase field.Cast structures and phases of Ti-(43-47)Al-8Nb-(1-2)Mn (at%) alloys have been studied by using scanning electron microscope and X-ray diffraction. Their solidification path and microstructure development during the solidification were analyzed. The experimental results show that the alloys with different Al contents form different macrostructures and microstructural morphologies. This indicates that the solidification paths are different with different Al contents. The alloy with 43Al forms equiaxed grain structure, and the solidification path is as follows: L → L β→β→α β→α β cores →α2 γ B2 cores. Whereas the alloy with 47Al forms columnar grain structure, and the solidification path is as follows: L → L β→α β L →α γ β cores →α2 γ B2 cores. The β phase is their primary solid phase and can be retained to ambient temperature. The alloy with 43Al solidifies completely into β phase. The peritectic reactions L β→α and L α→γ appear when the Al content increases to 47Al.     

Microstructural characterizations and mechanical properties of Mg-8Sn-1Al-1Zn-xCu alloys

Microstructural characterization and mechanical properties of as-cast Mg-8Sn-1Al-1Zn-xCu（x=0wt%, 1wt%, 1.5wt% and 2.0wt%） alloys were studied by OM, Pandat software, XRD, SEM, DSC and a standard universal testing machine. The experimental results indicate that adding Cu to TAZ811 alloy leads to the formation of the AlMgCu and Cu3 Sn phases. Tensile tests indicate that yield strength increases fi rstly and then decreases with increasing Cu content. The alloy with the addition of 1.5wt% Cu exhibits optimal mechanical properties among the studied alloys. The improved mechanical properties can be ascribed to the second phase strengthening and fi ne-grain strengthening mechanisms resulting from the more dispersed second phases and smaller grain size, respectively. The decrease in ultimate tensile strength and elongation of TAZ811-2.0wt% Cu alloy at room temperature is ascribed to the formation of continuous AlMgCu and coarse Mg2 Sn phases in the liquid state.     

High temperature scaling of Ni-15Cu-5Al alloy in 1×105 Pa pure oxygen

The oxidation of the ternary alloy Ni-15Cu-5Al in 1×10⁵ Pa pure oxygen at 700 °C and 800 °C was studied. The results show that the behavior of the Ni-rich alloy is similar to that of the binary Ni-Al alloy with the same Al content in the form of an external NiO layer coupled to the internal oxidation of aluminium. The presence of 15% (mole fraction) Cu cannot modify substantially the values of relevant parameters affecting the transition from the internal to the external oxidation of aluminium. The presence of 5% Al reduces the oxidation rate of the corresponding Ni-Cu alloy during the whole oxidation stages, though 5% Al is still insufficient to form protective external alumina scales. Foundation item: Project (50071058; 50271079) supported by the National Natural Science Foundation of China     

Sr对Mg-5Sn-5Zn铸造镁合金组织的影响

通过光学显微镜、扫描电镜和X射线衍射仪研究了Mg-5Sn-5Zn-xSr（x=0,0.5,1,2）4种铸造镁合金的显微组织和相组成.结果表明：在Mg-5Sn-5Zn合金中加入质量分数为0.5%～2%的Sr元素后,不但能够缩小α-Mg枝晶间距,而且还能形成三元相MgSnSr.随着Sr含量的增加,在晶界析出的Mg2Sn相减少,晶内的MgSnSr相增加。合金中的MgZn相与Mg2Sn相依附在一起,大多数的MgZn相以α-Mg＋MgZn相的共晶方式存在.     

Co对K4169合金凝固组织及元素偏析的影响

为研究Co对K4169合金凝固过程的影响,利用手工电弧炉熔炼制备了Co质量分数为0.5%～0.8%的合金,采用扫描电镜(SEM)、能谱仪(EDS)和电子探针(EPMA)对合金的凝固组织及元素偏析进行了研究.SEM观察结果表明,Co能强烈促进Laves相的形成,缩小合金枝晶间偏析区;随着Co质量分数从0.5%增加到0.8%,Laves相由小块状变为筛网状且数量明显增多.经SEM+EDS能谱和EPMA面扫描分析表明,Co能降低Nb在基体中的质量浓度,同时也能降低Fe和Cr在Laves相中的质量浓度而提高Nb、Mo、Ti在Laves相中的质量浓度,因而促进Laves相的析出.分析认为,过多增加Co质量分数对改善合金凝固组织的作用不大.     

Effects of Y Content on the Microstructures and Mechanical Properties of Mg-5Zn-xY-0.6Zr Alloys

Three as-cast and as-extruded Mg-5Zn-x Y-0.6Zr(x=5 wt%, 8 wt%, 11 wt%) alloys were prepared, and the effects of Y content on the microstructures and mechanical properties of the alloys were investigated. The results show that the investigated Mg-Zn-Y-Zr alloys mainly consist of a-Mg, X-Mg12 YZn and minor amount of W-Mg_3Y_2Zn_3 phases. The volume fraction of X-Mg_(12) YZn phase increases and that of W-Mg_3Y_2Zn_3 phase decreases with the rising of Y content in the alloys. The as-extruded Mg-5Zn-11Y-0.6Zr alloy owns the optimal ultimate tensile strength and yield strength of 429 and 351 MPa, respectively. Mg-5Zn-5Y-0.6Zr alloy owns the maximum elongation of 13.6%.     

Microstructure and property of the Ti-24Al-15Nb-1.5Mo/TC11 joint welded by electron beam welding

The Ti-24Al-15Nb-1.5Mo alloy,in the as-forged and heat-treated states,was joined to the as-forged TC11 titanium alloy by electron beam welding with the heat inputs of 135 and 150 kJ/m.Then the microstructure and property of the Ti-24Al-15Nb-1.5Mo/TC11 welding interface were investigated.The results show that the phase constitution of the weld is not related to the heat input,and is mainly composed of α' phase.Moreover,the intermetallic phases of Ti2AlNb,MoNb,Nb3Al,and TiAl3 are formed in the weld zone.There...     

熔体温度处理对磷铜变质Al-20%Si组织的影响

研究熔体温度处理工艺（包括熔体混合及熔体过热处理）与磷铜变质对Al-20%Si合金中硅相形态的影响。结果表明：在本试验条件下,单纯添加磷铜变质剂的Al-20%Si合金,当添加其合金质量的0.4%时,初晶硅由未变质前的97μm减小到65μm,减小了33%;当将熔体温度处理工艺与磷变质处理相结合时,此时Al-20%Si合金中的初晶硅尺寸减小至36μm,减小了62%,且钝化现象显著,弥散分布于α-Al基体上,共晶硅也由未变质前的长针状变为短纤维状和点状。     

Precipitation of ordered α2 phase in a near—α titanium alloy with duplex microstructure

The precipitation of ordered α2 phase in a near-αTi-6.3Al-4.8Sn-2.0Zr-1.0Mo-=0.34Si-0.9Nd(mass fraction)alloy with duplex microstructure,during aging at various temperatures,was investigated.It is concluded that the preciptitation and growth of the α2 Phase can be controlled by suitable selection of the aging temperature,Aging at higher temperatures can result in the uniform precipitation and growth of α2 ordered phase in αp whereas the α2 ordered phase precipitated only at the lamella boundaries and dislocations in β.Aging at a moderate temperature can promote the tendency of uniform precipitation of α2 phase in both αp and β1,Aging at a relatively low temperature is suitable for the uniform precipitation and growth of fine α2 particles throughout both the αp and βt matrix.     

压铸铝合金AlSi_9Cu_3的铁金属间化合物对高速钢刀具钻削磨损特性的影响

研究了在无润滑条件下,压铸铝合金A lSi9Cu3的铁金属间化合物对高速钢刀具钻削磨损特性的影响。结果表明:当合金中铁的质量分数较低时(w(Fe)<0.6%),铁金属间化合物以细小的多边形形状铁相为主,刀具后刀面磨损机制主要为塑性变形磨损,磨损量较大;当0.6%0.8%时,汉字状和多边形状铁相明显增多,呈薄片晶状的β相A l5FeSi出现,磨粒磨损成为主要的磨损机制,磨损量变大。粘着磨损和磨粒磨损共存的磨损机制是钻削压铸铝合金刀具合理的磨损机制。