AlCuFe共晶合金的显微组织和力学性能（英文）

制备特殊用途的AlCuFe合金,评估生长速率变化导致的结果,因为材料生长速率不同而引起的共晶间距(显微组织)的变化会影响其力学、电和热性能。为了研究AlCuFe合金的显微组织,在恒定的温度梯度(G=8.50 K/mm)和5种不同的生长速率(V=8.25, 16.60, 41.65, 90.05, 164.80μm/s)下,通过定向凝固法制备共晶成分的Al-32.5%Cu-0.5%Fe(质量分数)合金。得到生长速率对共晶间距影响,并通过对显微组织变化的回归分析及Hall-Petch关系得出显微硬度和极限拉伸强度。结果表明,尽管生长速率增加约20倍,但共晶间距却减少约5个数量级,而生长速率和显微组织变化导致的力学性能变化约为1.5个数量级。     

Influence of Nb on microstructure and mechanical properties of Ti-Sn ultrafine eutectic alloy

In this study, A series of the high strength (T₈₂Sn₁₈)_100-xNb_x (x=0, 1, 3, 5, and 9 at%) ultrafine eutectic alloys with large plasticity are developed by suction casting method. The Ti₈₂Sn₁₈ binary eutectic alloy consists of a mixture of a hcp Ti₃Sn and a α-Ti phases having the plate-like lamellar type duplex structure with micro scaled eutectic colony. From the (T₈₂Sn₁₈)₉₇Nb₃, the alloy display structural heterogeneous distribution of ultrafine-scaled phases composed of β-Ti(Nb) solid solution surrounded by alternating plate-like shaped Ti₃Sn and α-Ti phases. With increasing Nb content, the volume fraction of β-Ti is continuously increased, which induced improving mechanical properties both strength and plasticity. Especially, (Ti₈₂Sn₁₈)₉₁Nb₉ alloy has the outstanding combination of the high strength (σ _y ≈1.1 GPa) and large plasticity (ε _p ≈36%) at room temperature.     

Effect of Gallium on microstructure and mechanical properties of Nb–Si eutectic alloy

In this paper, we report a significant improvement in mechanical properties of near eutectic Nb–Si alloys by addition of Gallium (Ga) and control of microstructural length scale. A comparative study of two alloys Nb-18.79 at.%Si and Nb-20.2 at.%Si–2.7 at.%Ga were carried out. The microstructure refinements were carried out by vacuum suction casting in water cooled thick copper mold. It is shown that addition of Ga suppresses Nb₃Si phase and promotes β-Nb₅Si₃ phase. The microstructural length scale and in particular eutectic spacing reduces significantly to 50–100 nm in suction cast ternary alloys. Compression test shows a strength of 2.8 ± 0.1 GPa and plasticity of 4.3 ± 0.03%. In comparison, the binary Nb-18.79 at.%Si alloy processed under identical conditions exhibit coarser length scale (300–400 nm) and brittle behavior. The fracture toughness of Ga containing suction cast alloy shows a value of 24.11 ± 0.5 MPa√m representing a major improvement for bulk Nb–Si eutectic alloy.     

固溶处理对准共晶Al-Si合金显微组织及力学性能的影响

通过金相显微镜、差示扫描量热分析以及显微硬度测试等研究固溶温度和固溶时间对挤压铸造的ZAlSi12CuMgNi铝合金的显微组织和力学性能变化的影响。结果发现:在固溶过程中,强化相逐渐溶解,共晶Si逐渐细化、弥散,块状初晶Si趋于圆整化;保温时间过长,细化后的Si会发生聚集、粗化、长大,块状Si圆整度下降以及α(Al)晶粒长大等现象;随着固溶温度的上升,强化相的溶解和Si相的粒化、圆整化的时间会缩短,且Si相的细化程度和弥散程度更高,而Si相粗化和α(Al)晶粒长大的速度也会增大;在不同固溶温度下,α(Al)固溶体的力学性能随保温时间的延长而呈现不同形式的下降趋势;挤压铸造的ZAlSi12CuMgNi铝合金的最佳固溶处理工艺为525-530℃,保温时间为2.5-3h。     

Effects of rare earth elements on the microstructure and mechanical properties of NiAl-based eutectic alloy

The effects of rare earth elements (REEs) (like Y, Ce, Nd and Dy) on the microstructure and mechanical properties of cast NiAl–28Cr–5.5Mo–0.5Hf alloy were investigated. The results suggest that the microstructure of REEs-doped alloys gradually refines with increasing REEs addition and the appropriate addition of REEs can improve the compressive ductility and yield strength at room temperature. In addition, REEs additions increase the elevated temperature strength and deformation ability of the alloys. The elevated temperature compression deformation behavior of Nd-doped alloy can be properly described by power-law equation.     

Al-3P和Al-5Ti复合变质共晶铝硅合金的组织与性能

采用Al-3P和0.2 mass％Al-5Ti对共晶铝硅合金进行复合变质处理,并对复合变质前后共晶铝硅合金的显微组织和力学性能进行了分析和测试.结果 表明,Al-3P加入量和变质处理温度对共晶铝硅合金的显微组织和力学性能有明显影响.在700℃下采用0.6 mass％ Al-3P和0.2 mass％Al-5Ti对共晶铝硅...     

T6热处理对共晶Al-Si合金力学性能、耐磨和抗蚀性能的影响(英文)

对共晶Al-Si合金的耐磨、抗蚀性能进行研究。通过控制T6热处理参数来改变共晶Al-Si合金的组织,研究组织变化对合金的硬度、强度和拉伸性能的影响,以及对抗冲蚀和腐蚀性能的影响。采用Al-Si合金制备了一典型的农机零部件。并将Al-Si合金与常用的农机用铝材的性能进行比较。结果表明,合金的化学成分、显微组织、载荷、滑动距离和试验环境对材料的耐磨、抗冲蚀和腐蚀性能有很大的影响。铸态Al-Si合金的性能要明显优于传统的铝材,而且T6热处理能够改善Al-Si合金的性能。因此,可采用Al-Si合金来替代传统的铝材制造农机。     

Al-Cu-Ce合金的微观组织与力学性能

采用X射线衍射、金相显微镜、扫描电镜、能谱分析及拉伸性能测试等方法,研究3种成分Al-Cu-Ce合金的显微组织与力学性能。结果表明:铸态Al-14Cu-7Ce合金由α-Al+Al8CeCu4片状共晶组成,而Al-10Cu-5Ce、Al-18Cu-9Ce合金中除含有α-Al+Al8CeCu4共晶组织外,还分别含有α-Al和Al8CeCu4初生相。铸态Al-14Cu-7Ce合金具有优良耐热性能,即使550℃×3 h退火后仍能保持约360 MPa的抗拉强度,退火导致合金强度下降的主要原因是高温下共晶Al8CeCu4相的球化。经充分球化退火后,Al-Cu-Ce合金能获得良好的热轧、冷轧变形能力,并且变形态合金也具有良好的耐热性能,因而Al-Cu-Ce合金有望成为一种兼具铸造和变形两用的新型耐热铝合金。     

Fabrication and mechanical properties of high-performance aluminum alloy

High-performance Al–Cu–Mg alloy was fabricated by high-energy ball milling, sintering, and hot extrusion. The microstructure and mechanical properties of the material were preliminarily investigated. Results show that the formation of liquid phase during sintering promotes the densification of the aluminum powders. A97.1 % theoretical density is achieved in this alloy after sintering. The material shows excellent mechanical properties after extrusion and heat treatment. The ultimate tensile strength and yield strength of the extruded samples with heat treatment are 613 and 465 MPa, respectively.     

Atomic bonding and mechanical properties of Al-Mg-Zr-Sc alloy

The valence electron structures of AI-Mg alloy with minor Sc and Zr were calculated according to the empirical electron theory(EET) in solid. The results show that because of the strong interaction of AI atom with Zr and Sc atom in melting during solidification, the Al3 Sc and Al3 (Sc1-xZrx) particles which act as heterogeneous nuclear are firstly crystallized in alloy to make grains refine. In progress of solidification, the Al-Sc, Al-Zr-Sc segregation regions are formed in solid solution matrix of Al-Mg alloy owing to the strong interaction of Al atom with Zr, Sc atoms in bulk of alloy, so in the following homogenization treatment, the finer dispersed Al3Sc and Al3 (Sc1-xZrx) second-particles which are coherence with the matrix are precipitated in the segregation region. These finer secondparticles with the strong Al—Zr, Al—Sc covalent bonds can strengthen the covalent bonds in matrix of the alloy, and also enhance the hardness and strength of Al-Mg alloy. Those finer second-particles precipitated in interface of sub-grains can also strengthen the covalence bonds there, and effectively hinder the interface of sub grains from migrating and restrain the sub-grains from growing, and cause better thermal stability of Al-Mg alloy.     

Effects of Hf additions on high-temperature mechanical properties of a directionally solidified NiAl/Cr(Mo) eutectic alloy

In order to improve the high-temperature mechanical properties of NiAl/Cr(Mo) alloys, the effects of Hf additions on microstructure and mechanical properties were systemically examined. Two directionally solidified alloys with composition of Ni-32Al-28Cr-(6−x)Mo-xHf (x = 0.2 and 0.5 at.%, respectively), named as 0.2Hf and 0.5Hf hereafter, were prepared. The Hf additions disturbed the cellular structure. The 0.2Hf alloy consisted of dendritic structure, while the 0.5Hf alloy had an intercellular structure. In the 0.5Hf alloy, the Ni₂AlHf and Ni₁₆Hf₆Si₇ precipitates were also confirmed. The high-temperature strength and brittle-to-ductile transition temperature (BDTT) increased with increasing of Hf additions, due to the different strengthening mechanism. In contrast, the ductility and creep resistance decreased with increasing of Hf because of the disturbance of cellular structure.     

机械合金化制备Cu-0.5Wt%Nb合金组织与性能的研究

采用机械合金化法制备了Cu-0.5wt％Nb纳米弥散强化铜合金。通过金相、透射电镜观察了该合金粉末态、冷轧态及不同温度退火后合金的组织结构变化。通过测量该合金不同状态的硬度及相对电导率,实验结果表明,其冷轧态硬度较高(可达160kg/mm2),随退火温度升高硬度呈缓慢下降趋势;900℃退火后,硬度仍可达91kg/mm2,表明此合金抗高温软化性能较好.此外该合金相对电导率最高可达89% IACS,这进一步说明利用机械合金化法制备的Cu-0.5wt%Nb合金具有优越的综合性能.     

高强Mg-Gd-Y-Zn-Zr合金的微观组织和力学性能

通过金属模铸、热挤压和时效处理(T5)工艺过程制备出高强Mg-7Gd-4Y-1.6Zn-0.5Zr合金,并利用光学显微镜、XRD、SEM及TEM分析研究Mg合金不同状态下的显微组织和力学性能。结果表明:Mg-7Gd-4Y-1.6Zn-0.5Zr合金的铸态组织主要由α-Mg基体和沿晶界分布的片层状第二相Mg12Zn(Gd,Y)组成,经过热挤压变形后,合金晶粒显著细化,时效处理过程中Mg12Zn(Gd,Y)相上析出少量细小的颗粒状Mg3Zn3(Gd,Y)2相。时效态合金的抗拉强度、屈服强度和伸长率分别达到446 MPa、399 MPa和6.1%,其强化方式主要为细晶强化和第二相强化。     

Al-Si共晶对Mg-12Li合金微观组织及性能的影响

对比分析了添加Al和Al-Si共晶的Mg-12Li合金铸态及轧制态的组织和性能,研究Al-Si共晶对合金组织性能的影响。结果表明,当加入Al-Si共晶后,Mg-12Li-3(Al-Si)组织中开始有白色析出物（脆性相Mg2Si）析出,形成的中间化合物依次为AlLi、MgLi2Al、Mg2Si。该合金抗拉强度为230 MPa,伸长率为25.5%,性能接近添加了RE的镁锂合金,成本得到明显的降低。当Al-Si共晶量达到6%时,合金的力学性能会下降。     

Effect of phosphide eutectic on the properties of a cast iron alloy

Conclusions The most technologically advanced material for valve seats of internal-combustion engines are the phosphorus-alloyed cast irons strengthened by a reinforcing phase consisting of the phosphide eutectic and cementite, the ratio between which depends on the Cr to P ratio, the technology of the modification, and the cooling rate of the castings.The optimum structure of the cast iron for valve seats, which produces a combination of good machinability and high wear resistance is the troostomartensitic or troostosorbitic matrix with a network of the FÉ5-type phosphide eutectic (with cementite lamellae), and clusters of graphite combined with fine- and medium-size flakes with less than 5% of the structurally free graphite. The optimum combination of wear resistance, machinability, and strength of the valve seats is attained at the ratio Cr/P=3–4 and modification by 0.5–0.8% ferrosilicon. The wear of the phosphorous-containing cast iron with a troostomartensitic or troostosorbitic matrix is determined by the amount of the cementite in the ledeburite and, when its content is small or it is absent, by the type of the phosphide eutectic. A phosphorus-containing cast iron of the type of 360S3KhGMD has been suggested which has gone into production. It has the composition: 3.5–3.8% C, 2.5–3.0% Si, 0.7–1.0% Mn, 0.9–1.2% Cr, 0.9–1.2% Mo, 0.3–0.6% P, 0.7–1.2% Cu, and up to 0.1% S.Melitopol Automobile Factory, Zaporozh'e Machine-Construction Institute. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 3, pp. 23–25, March, 1993.     

精铸Ti-Al-Zr合金的显微组织和力学性能

用陶瓷型壳浇注了Ti Al Zr合金 ,研究了精铸Ti Al Zr合金的相组成、铸造显微组织、室温和高温力学性能及断口形貌。结果显示 ,精铸Ti Al Zr合金属于近α型 ,其铸态组织为网篮状魏氏组织 ,具有较好的室温和高温性能。Ti Al Zr合金的室温力学性能为 :抗拉强度 1 0 57.5MPa ,屈服强度 995MPa ,延伸率 1 8.45% ;50 0℃时的力学性能为 :抗拉强度 658.7MPa ,屈服强度 538.9MPa ,延伸率 1 6.5%。该合金室温断口以延性断裂为主 ,伴有部分解理断裂 ,而高温拉伸断口为延性断裂。     

Fe-40Ni-Ti合金的组织及力学性能

利用金相观察、硬度测量、热模拟技术及透射电子显微术(TEM),研究了Fe-40Ni-Ti合金的组织及力学性能。结果表明：Fe-40Ni-Ti合金在室温下仍然是面心立方结构,晶粒中有少量孪晶组织。锻造后试样中有两类析出：一类是在光镜下可直接观察到的1 μm以上合金凝固过程中形成的TiN颗粒,另一类是在TEM电镜下发现的轧制应变诱导析出,尺寸在20 nm以下的TiN颗粒。合金在不同温度保温后冷却到室温的硬度变化不明显。在850 ℃变形后保温过程中,合金发生应变诱导析出现象。     

低合金化Mg-Zn-Y合金的显微组织与力学性能研究

本文通过常规铸造制备了三种成分的低合金化Mg-Zn-Y (Mg-0.6Zn-0.1Y、Mg-1.3Zn-0.1Y、Mg-2.0Zn-0.1Y,wt.%),并对其进行低温慢速挤压（140℃,0.1mm/s）。研究结果表明：随Zn含量的增加,挤压前合金的晶粒尺寸逐渐减少。挤压后合金晶粒显著细化,形成弥散的纳米析出相,同时随Zn含量的增加合金的再结晶程度与纳米析出相的数量均增加,基面织构强度则无显著变化。挤压后合金的力学性能得到大幅提升,其中Mg-2.0Zn-0.1Y合金的屈服强度、抗拉强度和延伸率分别达到406.4MPa、424.5MPa、12.2%。随Zn含量增加,Mg-Zn-Y合金的延伸率显著增加,其断口形貌由解理面转变为细小的韧窝,断裂方式由解理断裂转变为韧性断裂。     

新型Al-Mg-Si-Cu合金的热变形行为及力学性能

采用热模拟研究一种新型Al-Mg-Si-Cu合金的热变形行为,制定该合金的低温快速挤压工艺和在线热处理制度,利用电子万能实验机、光学显微镜、扫描电镜对合金的力学性能和组织进行分析。结果表明:新型Al-Mg-Si-Cu合金为正应变速率敏感材料;该合金的热压缩变形流变应力行为可用双曲正弦形式的本构方程来描述,也可用Zener-Hollomon参数来描述,其变形激活能为189.82kJ/mol;随着热变形温度的升高和应变速率的减小,合金的主要软化机制逐步由动态回复转变为动态再结晶;合金低温快速挤压后,经过在线风淬停留3h,然后200℃人工时效3h,其抗拉强度达到305MPa,屈服强度达到265MPa。