T6热处理对SiCp/Al复合材料摩擦磨损性能的影响

采用粉末冶金法制备出不同SiC颗粒体积分数(30%、35%和40%)的SiCp/Al复合材料。采用MMU-5GA微机控制真空高温摩擦磨损试验机对比研究SiCp/Al复合材料在不同体积分数以及T6热处理前后情况下平均摩擦因数和磨损率的变化,通过扫描电镜分析了SiCp/Al复合材料表面磨损形貌,探讨了摩擦磨损机理。试验结果表明,SiC颗粒体积分数在30%~40%变化时,随其体积分数增加耐磨性下降。SiC颗粒体积分数在30%~35%范围内,SiC颗粒与基体结合较好,SiC颗粒作为硬质点起到抵抗磨损和限制基体合金塑性变形产生磨损的双重作用;但SiC含量过多时,颗粒与基体的结合不紧密,磨损时颗粒极易脱落,复合材料耐磨性降低;T6热处理后复合材料的平均摩擦因数和磨损率均降低,这是由于热处理后试样强度及硬度提高,从而提高了试样的耐磨性;常温下复合材料在磨损初期的磨损机理主要以磨粒磨损为主,而在磨损期则为磨粒磨损与剥落磨损共存。     

热处理工艺对Fe-12Mn-xNi-4C-3.5Si铸铁组织与性能的影响

熔炼出3种不同镍含量的Fe-12Mn-xNi-4C-3.5Si(x=5%,10%,15%)系合金铸铁,研究了不同的热处理工艺对合金组织和性能的影响.结果表明,合金中碳元素的石墨化倾向随着Ni含量增加而增大;经高温退火处理后,合金组织由奥氏体基体、石墨及少量点状碳化物组成;合金中Ni含量越高,碳化物在高温下越容易分解.淬火处理后由于获得了单一奥氏体基体,合金的冲击韧度和抗弯强度均有较大提高,Ni含量越高韧性提高越显著,经900 ℃、8 h保温后淬火的Fe-12Mn-15Ni-4C-3.5Si合金,在三点弯曲试验中可弯成120°不裂,冲击韧度提高至50.2 J·cm~(-2),淬火后由于碳化物被消除,合金的硬度下降,磨损率增大.     

Si质量分数对RE-Al-Fe合金的组织及其性能的影响

通过在RE-Al-Fe合金(3%RE-Al-Fe)中加入不同质量分数的硅铁,探究Si质量分数对RE-Al-Fe合金的组织及性能的影响。利用扫描电子显微镜和X射线衍射仪分别测试样品的显微组织和相结构。试验结果表明:在3%RE-Al-Fe合金中,不添加Si的合金由FeAl3、Fe2Al5和RE-Al-Fe相组成,随着Si的质量分数(2%、4%、6%、8%)逐渐增加,合金中均出现铝铁硅(Al-Fe-Si)相;随着Si质量分数的增加,Al-Fe-Si相的衍射峰先增强后减弱,当Si质量分数达到6%时衍射峰强度最大;随着Si质量分数的增加,硬度值的变化趋势是先增大后减小,当Si质量分数达到6%时硬度值最大为92HV。     

Effect of heat treatment on mechanical and wear properties of Zn–40Al–2Cu–2Si alloy

In order to determine the effect of heat treatment on the mechanical and wear properties of Zn–40Al– 2Cu–2Si alloy, different heat treatments including homogenization followed by air-cooling (H1), homogenization followed by furnace-cooling (H2), stabilization (T5) and quench–aging (T6 and T7) were applied. The effects of these heat treatments on the mechanical and tribological properties of the alloy were studied by metallography and, mechanical and wear tests in comparison with SAE 65 bronze. The wear tests were performed using a block on cylinder type test apparatus. The hardness, tensile strength and compressive strength of the alloy increase by the application of H1 and T6 heat treatments, and all the heat treatments except T6, increase its elongation to fracture. H1, T5 and T6 heat treatments cause a reduction in friction coefficient and wear volume of the alloy. However, this alloy exhibits the lowest friction coefficient and wear volume after T6 heat treatment. Therefore, T6 heat treatment appears to be the best process for the lubricated tribological applications of this alloy at a pressure of 14 MPa. However, Zn–40Al–2Cu–2Si alloy in the as-cast and heat-treated conditions shows lower wear loss or higher wear resistance than the bronze.     

Micromechanisms and mechanics of ultra-mild wear in Al–Si alloys

The micromechanisms that control the sliding wear behavior of Al–Si alloys tested under ultra-mild wear conditions were characterized using optical profilometry and electron microscopy, and analyzed by means of a contact mechanics model. A series of damage events occurred to the chemically etched surfaces of an Al–25% Si alloy, subjected to boundary-lubricated contact during pin-on-disk tests, in the following sequence: the fracture and/or sinking-in of silicon particles into the aluminum matrix accompanied by the formation of aluminum pile-ups; aluminum wear (rapid wear period) and the development of an oil residue layer on the contact surface. Compared to an Al–11% Si with similar silicon morphology but lower hardness, the Al–25% Si delayed aluminum wear more effectively. Once an oil residue layer supported by a subsurface microstructure consisting of ultra-fine aluminum grains was formed, both alloys displayed decreasing wear rates.     

Effects of Pb and Cu additives on microstructure and wear corrosion resistance behaviour of PM Al–Si alloys

Abstract

The wear and wear corrosion resistance behaviour of Al–20Si–XPb–YCu (X=0–10 wt-%, Y=0–3 wt-%) alloys fabricated by a powder metallurgy (PM) technique and subsequent heat treatments were evaluated by a block on ring tribotest. The microstructure of all aluminium alloys was observed by optical microscopy and scanning electron microscopy with X-ray energy dispersive spectroscopy. The effects of applied potentials and environments including dry air and 3.5 wt-%NaCl aqueous solution were studied. The results of microstructure analysis indicated that Pb exhibited a bimodal distribution in the Pb containing alloys, and Cu particles become to form the intermetallic phase CuAl₂. Furthermore, the hardness rises significantly for both Pb and Cu containing alloys only after solid solution quenching treatment. The wear and corrosion results showed that the addition of both lead and copper would improve the wear resistance but lead to a higher corrosion rate whereas heat treatment had a beneficial effect of reducing the corrosion rate of most alloys with the exception of Al–Si alloy. Furthermore, by comparison of all alloys after heat treatment, the wear corrosion resistance of Al–Si alloy was inferior to the other alloys; consequent additions of Pb and Cu further improved its wear corrosion resistance. Moreover, at an anodic potential, the wear corrosion rate and current density of both Al–Si and Al–Si–Cu alloys containing particle Pb decrease significantly owing to a corrosion product layer composed of Al, O and Pb elements.     

Microstructure,mechanical properties and two-body abrasive wear behaviour of hypereutectic Al—Si—SiC composite

The microstructure, mechanical properties, and the effects of sliding distance and material removal mechanism on two-body abrasive wear behaviour of hypereutectic Al—Si—SiC composite and its matrix alloy were investigated. The hypereutectic Al—Si—SiC composite was prepared by stir casting route. The hardness, ultimate tensile strength and yield strength of the composite are increased by 17%, 38%, and 30% respectively compared with those of the matrix alloy, while the elongation of the composite is decreased by 48% compared with that of the matrix alloy. The wear rate of the materials is increased with increasing the abrasive size and the applied load and does not vary with the sliding distance. The wear surfaces and wear debris of the materials were characterized by high-resolution field emission scanning electron microscopy (HR FESEM) and wear mechanism was analyzed for low and high load regimes.     

Effect of Si content on surface hardening of Al–Si alloy by shot peening treatment

The effect of Si content was investigated for Al–Si alloys (Al-7%, 11%, 18%Si) by shot peening process. The hardness increment by shot peening increased as the Si contents in Al–Si alloys increased. Finer Si particles and more dense distribution of those were observed in Al–18%Si than Al–7%Si. As Si contents of Al–Si alloys increased, grain size at the surface area of Al–Si alloy decreased. Higher hardness of Al–Si alloy with higher Si content could be attributable to more dense and refine Si particles and accelerated grain refinement during severe deformation.     

原位合成多元硼化物对Al0.5CoCrCuFeNiBx高熵合金硬度与耐磨性能的影响

本文研究了Al0.5CoCrCuFeNiBx (x=0-1)的组织、相组成、硬度及耐磨性能。并预测了Al0.5CoCrCuFeNiBx (x=0-1)中简单固溶体形成规律。未添加硼元素的合金具有简单FCC固溶体结构。添加硼元素后,合金由简单FCC固溶体及多元硼化物组成。硼以硼化物形式析出,没有固溶到FCC固溶体中,因而添加硼对FCC固溶体的晶格常数无影响。硼化物的析出使合金的硬度提高,并且硬度随着硼含量的增加而呈线性增加。当硼含量x?0.4时,合多的磨耗阻变化不明显,但当硼含量x?0.6时,合金的磨耗阻抗随着硼含量增加而呈线性增加。 随着硼含量的增加,合金的磨损机制由粘着磨损转变为氧化磨损。合金硬度与耐磨性能的提高是高硬度的粗大硼化物与韧性的FCC固溶体基体共同作用的结果。     

激光熔覆制备高熵合金涂层的研究进展

激光熔覆技术具有高的冷却速度、低的稀释率、涂层与基体冶金结合等优点,采用激光熔覆技术制备耐磨性和耐腐蚀好的高熵合金涂层是近几年高熵合金领域的研究热点之一。首先概括了激光熔覆技术制备的高熵合金体系及组织结构特征,大多高熵合金涂层以固溶相为主,少数合金涂层形成了非晶相,与熔炼制备高熵合金块体材料相比,涂层组织具有均匀、细小致密等特点。然后介绍了涂层的性能特征,涂层具有较高的硬度、良好的耐磨性,同时指明高耐磨性涂层不仅具有高的硬度,同时还需要具有一定的塑韧性。涂层合金中大多包含有Al、Cr、Si和Co等形成稳定氧化膜的元素,呈现优异的抗腐蚀性能。随后重点概述了合金元素（Al、Mo、V、Ti、B、Ni、Nb和Cu等）、熔覆工艺参数（激光功率、扫描速度和预制层粉末厚度）和热处理工艺对涂层组织结构和性能的影响规律。其中,熔覆工艺参数对涂层组织结构和性能的影响研究相对较少,将是未来研究的重点内容之一。最后对激光熔覆技术制备高熵合金涂层存在的问题和未来的研究方向做了展望。     

Effects of magnesium content on phase constituents of Al-Mg-Si-Cu alloys

1 Introduction The heat-treatable Al-Mg-Si-Cu(6000 series) alloys used as automotive body sheet materials are being brought to practical use more and more in North American and Europe, and becoming optimal materials caused by mass reduction of automotive …     

Si、Cu和热处理工艺对Al-Si合金电导率的影响

通过电导率测量、金相观察、扫描电镜分析和X射线衍射分析,研究了Si含量、Cu含量和热处理工艺对Al-Si系铸造合金晶格常数和电性能的影响规律。结果表明:Si和Cu元素的添加会减小合金的电导率;当Si含量超过固溶极限后,Si含量的变化对晶格畸变程度影响不大,合金的电导率受Si相的体积百分数控制;而Cu在固溶极限内时,随其含量的增加,晶格畸变程度增大,合金的电导率可根据铝基体晶格常数的偏离量来评估;经过450℃,5 h+250,2 h热处理工艺,晶格畸变程度明显降低,合金的电导率有明显提高,增幅最高可达32%。     

硅酸铝短纤维增强Al-12Si合金复合材料的磨损行为

用挤压铸造法制备了低体积分数（３％～７％）的硅酸铝短纤维增强Ａｌ１２Ｓｉ合金复合材料,并利用销盘磨损试验机研究了材料在干摩擦条件下的磨损行为。磨损试验结果表明：硅酸铝短纤维加入到Ａｌ１２Ｓｉ合金明显提高抗磨损能力,随纤维体积分数的增加该复合材料的耐磨性逐渐增强。金相观察和测试表明：基体合金和复合材料的磨损区由硬化层和变形层组成,断裂的ＡｌＳｉ共晶相沿滑动方向重新分布排列形成了硬化层;而复合材料硬化层由于破断的硅酸铝纤维和破碎的ＡｌＳｉ共晶相的共同作用,使该硬化层硬度高于基体合金硬化层的硬度,从而使复合材料表现出优异的耐磨性。并根据试验结果提出了基体合金和复合材料的磨损机制模型     

Effect of heat treatment on interfacial and mechanical properties of A6022/A7075/A6022 roll-bonded multi-layer Al alloy sheets

Multi-layered Al alloy sheets can exhibit unique properties by the combination of properties of component materials. A poor corrosion resistance of high strength Al alloys can be complemented by having a protective surface with corrosion resistant Al alloys. Here, a special care should be taken regarding the heat treatment of multi-layered Al alloy sheets because dissimilar Al alloys may exhibit unexpected interfacial reactions upon heat treatment. In the present study, A6022/A7075/A6022 sheets were fabricated by a cold roll-bonding process, and the effect of the heat treatment on the microstructure and mechanical properties was examined. The solution treatment gave rise to the diffusion of Zn, Mg, Cu and Si elements across the core/clad interface. In particular, the pronounced diffusion of Zn, which is a major alloying element (for solid-solution strengthening) of the A7075 core, resulted in a gradual hardness change across the core/clad interface. Mg2Si precipitates and the precipitate free zone were also formed near the interface after the heat treatment. The heat-treated sheet showed high strengths and reasonable elongation without apparent deformation misfit or interfacial delamination during the tensile deformation. The high strength of the sheet was mainly due to the T4 and T6 heat treatment of the A7075 core.     

基于人工神经网络与遗传算法的Al-Mg-Si系合金抗拉强度预测模型

为了研究Al-Mg-Si系合金热处理制度和合金成分对力学性能的影响规律,采用人工神经网络（artificial neural network, ANN）和遗传算法（genetic algorithm, GA）相结合的方法,构建了Al-Mg-Si系合金强度预测模型（ANN-GA模型）。通过单因素和双因素分析,研究了合金元素含量和热处理工艺参数对铝合金抗拉强度的影响规律。结果表明,随着Si含量的增加,铝合金的抗拉强度呈现先降低后升高的趋势;随着Mg含量的增加、Cu含量的增加或者Fe含量的减少,铝合金的抗拉强度整体上呈现升高的趋势。双因素分析更能反映输入参数对铝合金抗拉强度的影响。Mg/Si比、Mg+Si总量和时效时间对Al-Mg-Si系合金力学性能的影响显著。铝合金的硬度随时间的变化趋势与ANN-GA模型的计算结果一致,峰值时效时间为29 h,相对误差为11.86%。     

Mg-9Zn—xAl合金的显微组织和力学性能

借助金相显微镜、扫描电镜、能谱分析仪、显微硬度计及电子万能试验机等研究了Mg-9Zn-xAl（x=2％、4％、6％）合金的显微组织和力学性能。试验结果表明：随着Al含量的增加,晶粒尺寸呈不断减小的趋势,合金中的第二相由断续状分布向连续网状转变;当Al含量为2％和4％时,合金主要由α-Mg基体相、τ-Mg32（Al,Zn）49相和MgZn相组成,当Al增加到6％时,合金主要由α-Mg基体相、τ-Mg32（Al,Zn）49相和少量Mg5Zn2A12相组成。抗拉强度随着Al含量的增加呈先增大后减小的趋势,当Al含量为4％时,抗拉强度为171MPa;伸长率和硬度随着Al含量的增加而逐渐增加,当Al含量为6％时,硬度为133HV。     

THE INFLUENCE OF C ON THE OXIDATION AND WEAR RESISTANCE OF Fe-Cr-Mn ALLOY AT HIGH TEMPERATURES

A kinetic oxidation test and an isothermal oxidation test of Fe-Cr-Mn alloys containing0.50％ to 2.69％ C were carried out at 800 and 660℃ in atmosphere.A high temperatureabrasive wear test of the alloys was also done in a self-made wear tester.A study of themorphology of the oxide film and the element distribution in the subsurface indicated that:(1) with increasing C content of the alloys the amount of eutectic carbide increased andthe Mu content in the matrix participating in the oxidation process decreased,resultingin an increase of the oxidation resistance of the alloys:(2) The high temperature wearresistance of the alloys was closely related to the bulk hardness of the alloy and theamount of eutectic carbide.The increase in hardness of the alloys increased the hightemperature wear resisance.However,it must be emphasized that the wear resistanteffect of the carbides depends strongly on the support provided by the matrix.     

Transient oxidation of multiphase Ni-Cr base alloys

Four commercially available Ni-Cr-based alloys used with porcelain enamels were studied. Major alloying elements were Al, Be, Si, B, Nb, and Mo. All alloys were multiphase. During heat treatments simulating enameling conditions, phase changes occurred in most alloys and were detected using hardness testing, differential thermal analysis (DTA), and microscopy. Oxidation of these alloys at 1000°Cfor 10 min produced an oxide layer consisting principally of chromium oxide, but the oxide morphology varied with each alloy depending on the alloy microstructure. Controlling alloy microstructure while keeping the overall composition unchanged may be a means of preventing wrinkled poorly adherent scales from forming.     

Cr/Al复合合金化Fe_3 Si基有序合金的制备及其力学性能

采用真空电弧熔炼/退火制备了Cr/Al复合合金化Fe3Si基有序合金。通过XRD、SEM对试样进行表征,同时对其显微硬度、压缩强度及弯曲强度等力学性能进行了综合分析。结果表明,Cr/Al复合合金化Fe3Si基有序合金主相仍为Fe3Si相。元素Al,Cr复合合金化较为明显的改善了Fe3Si基有序合金的脆性。Fe65Si25Cr5Al5的抗压和抗弯强度最高,这是因自身高的有序度而呈现的陶瓷性的高强度低应变量特征。有序合金表现出明显的解理断裂特征,Fe80 Si10 Cr5Al5表现出二次解理的特征,Fe75 Si15 Cr5 Al5和Fe70 Si20 Cr5 Al5在断裂时出现了一些韧性特征的撕裂棱,这应与自身适中的有序度有关。     

Si，La对Al-4．5Cu合金准固态凝固行为的影响

通过对合金的收缩应变和热裂抗力及准固态拉伸行为进行测试，研究了合金元素(Si，La)对Al-4．5Cu合金凝固行为的影响。结果表明，Si，La能使Al-4．5Cu的热裂倾向性降低；加入2％Si使合金的再辉现象非常严重，导致合金不可能有很高的强度而很快断裂：与其它Al-4．5Cu-Si合金相比，Al4．5Cu3Si合金具有很强的补缩能力，断裂应力值最高：La的加入能缩小二次枝晶间距，明显提高合金的抗热裂性能。