Al—Pb系耐磨合金的制造技术,组织结构及力学性能

本文综述了作为背析一代耐磨材料的Ａｌ－Ｐｂ系合金的各种制造方法，重点讨论了不同制造方法得到的组织结构以及耐磨性为主的力学性能。     

Al—Pb轴瓦合金的应用及研究进展

分析了Ａｌ－Ｐｂ合金的国内外发展状况，快速凝固制备技术，材料性能五组成，结构的相互关系，以及Ａｌ－Ｐｂ合金作为典型偏晶系合金的凝固过程和显微结构。     

双级雾化快速凝固工艺及其破碎机理

设计制造了由超音速气体雾化和旋转盘雾化组成的双级雾化装置，并对比有雾化处理进行分析，提出了旋转盘机械破碎模型。采用Ａｌ－２０Ｓｉ合金进行了工艺性试验，并采用Ａｌ－４．５Ｃｕ合金地该装置的冷却速度进行了测算。     

Al-Li合金真空精炼与成分变化规律的研究

研究了Ａｌ－Ｌｉ合金真空除氢规律，并对比研究了真空除氢过程中化学成分变化规律，为Ａｌ－Ｌｉ合金的生产提供了重要参数，并为研究新一代高韧Ａｌ－Ｌｉ合金打下了基础。     

球磨时间对机械合金化Al-8Ti合金组织的影响

采用机械合金化方法制备Ａｌ－Ｔｉ合金时，球磨时间影响粉体的粒度、结构和相组成，从而影响合金成型后的组织结构与性能。经过足够长时间球磨后，Ａｌ、Ｔｉ混合粉转变为单一Ａｌ（Ｔｉ）过饱和固溶体，且颗粒细小均匀；成型后可获得Ａｌ基体上弥散分布细小Ａｌ３Ｔｉ颗粒的Ａｌ－Ｔｉ合金。     

Ni3Al合金硼原子占位及晶界偏聚

依据ＬＩ２型金属间化合物八面体，四面体间隙的特点，并利用硬球模型计算了上述各类间隙的空球半径大小，发现Ｎｉ３Ａｌ合金中６Ｎｉ八面体间空球半径比其他间隙大，使硼原子在更易进入６Ｎｉ八间隙，由于富Ｎｉ－Ｎｉ３Ａｌ合金晶界比Ａｌ－Ｎｉ３Ａｌ合金有更我的６Ｎｉ八面体间隙，所以硼在富Ｎｉ－Ｎｉ３Ａｌ晶界偏聚较多，另外富Ａｌ－Ｎｉ３Ａｌ合金晶界原子间作用力比富Ｎｉ－Ｎｉ３Ａｌ合金晶界原子间作用力大，这也阻碍了     

TiAl基合金中的不连续粗化转变

为细化铸造ＴｉＡｌ基合金的显微组织,将成分为Ｔｉ－４４．９Ａｌ、Ｔｉ－４８Ａｌ以及Ｔｉ－４４．３Ａｌ－３．０Ｃｒ（ａｔ％）的三种合金在略高于Ｔｉ－Ａｌ共析温度的１１５０℃进行长时保温处理。结果表明,保温一定时间后,合金中的Ｔｉ３Ａｌ＋ＴｉＡｌ片层组织会发生三种类型的不连续粗化转变,转变结果均能在一定程度上细化合金的铸态晶粒尺寸,其中Ｔｉ－４４．３Ａｌ－３．０Ｃｒ合金的晶粒细化效果最佳。此外,Ａｌ含量的增加,合金元素Ｃｒ的加入等都会大大促进合金的不连续经转变过程。     

液态浸渗法制备Al_2O_3-SiO_2纤维/Al-Si复合材料

给出了硅酸铝（Ａｌ２Ｏ３－ＳｉＯ２）短纤维局部增强Ａｌ－Ｓｉ合金的液态浸渗制造工艺，并测试了该复合材料的强度以及摩擦磨损性能。试验表明，该复合材料的强度以及摩擦磨损性能均高于基体金属。     

球磨时间对机械合金化Al—8Ti合金组织的影响

采用机械合金化方法制备Ａｌ－Ｔｉ合金时，球磨时间粉体的粒度、结构和相组成，从而影响合金成型后的组织结构与性能。经过足够长时间球磨后，Ａｌ、Ｔｉ混合粉转变为单一Ａｌ（Ｔｉ）过饱和固溶体，且颗粒细小均匀；成型后可获得Ａｌ基体上弥散分布细小Ａｌ３Ｔｉ颗粒的Ａｌ－Ｔｉ合金。     

EXPLORATION ON THE FABRICATION OF BULK NANOCRYSTALLINE MATERIALS BY DIRECT-NANOCRYSTALLIZING METHOD ⅡTheoretical Calculation of Grain size of Metals sondified under Electropulsing

利用物理替代方法计算出球形核的形状因子ｋ１，推导出均质形核和无晶粒吞并时晶粒尺寸改变与电流密度的关系，计算了Ｐｂ，Ｓｎ，Ｃｕ，Ｆｅ，Ａｌ，Ｎｉ等纯金属用电流变技术直接制备块状纳米材料所需要的临界电流密度值，对Ｐｂ－Ｓｎ合金的计算表明本文的理论值与国外报导的结果基本一致。     

Wear characteristics of spray formed Al-alloys and their composites

In the present investigation, different Al based alloys such as Al–Si–Pb, Al–Si, Al–Si–Fe and 2014Al + SiC composites have been produced by spray forming process. The microstructural features of monolithic alloys and composite materials have been examined and their wear characteristics have been evaluated at different loads and sliding velocities. The microstructural features invariably showed a significant refinement of the primary phases and also modification of secondary phases in Al-alloys. The Pb particles in Al–Si–Pb alloy were observed to be uniformly distributed in the matrix phase besides decorating the grain boundaries. The spray formed composites showed uniform distribution of SiC particles in the matrix. It was observed that wear resistance of Al–Si alloy increases with increase in Pb content; however, there is not much improvement after addition of Pb more than 20%. The coefficient of friction reduced to 0.2 for the alloy containing 20%Pb. A sliding velocity of 1 ms⁻¹ was observed to be optimum for high wear resistance of these materials. Alloying elements such as Fe and Cu in Al–Si alloy lead to improved wear resistance compared to that of the base alloy. The addition of SiC in 2014Al alloy gave rise to considerable improvement in wear resistance but primarily in the low pressure regime. The wear rate seemed to decrease with increase in sliding velocity. The wear response of the materials has been discussed in light of their microstructural features and topographical observation of worn surfaces.     

Effect of in situ phases on microstructure and properties in Al–Bi immiscible alloy

Al–Bi immiscible alloy is of particular interest as potential self-lubricating wear materials with a homogeneous distribution of minority phase. However, it is difficult to obtain a homogeneous microstructure by conventional casting methods due to liquid phase separation of Al–Bi immiscible alloy. We have developed a new strategy to restrain liquid phase separation and improve the properties of Al–Bi immiscible alloy by in situ phases. The in situ AlB₂ phase acts as heterogeneous nucleation site to accelerate the nucleation and slow down the velocity of the Bi-rich droplet, resulting in a significant size reduction and a homogeneous microstructure of Al–Bi immiscible alloy. The self-lubricating wear resistance of Al–Bi immiscible alloy can be further enhanced by in situ Al₂Cuphase.     

Wear behaviour of 85Al–10La–5Ni alloy prepared by powder metallurgy

Abstract

The dry wear behaviour of 85Al–10La–5Ni (at.-%) alloy hot pressed has been studied. The result shows that 85Al–10La–5Ni alloy possessed excellent wear resistance. The wear resistance of the alloy pressed at 773 K is three times as high as that of the A355 aluminium alloy. The fine high hardness intermetallic compounds contribute to the wear resistance of the alloy.     

Al2O3/Ti6Al4V diffusion bonding joints using Ag–Cu interlayer

Ceramic materials, such us alumina, are widely used for wear resistant and industrial components as in aircraft applications. On the other hand, Ti6Al4V is commonly used for aeronautical applications, due to its superplasticity, low weight and high mechanical resistance but has poor wear resistance because of its low resistance to plastic shearing. For these reasons numerous techniques have been developed to improve its wear resistance including joining to ceramic materials. Ceramics and alloys can be joined by several different processes and the use of an interlayer can further facilitate this process. In the present work Al₂O₃ and Ti6Al4V alloy have been diffusion bonded using a (Ag–Cu) interlayer. Identification of intermetallic phases formed within the bonded region enables the mechanical behaviour of the joints to be explained. These intermetallic phases are related to the bonding conditions applied (750 °C, 3 MPa with bonding times varied from 10 to 60 min).     

The wear of aluminium-based journal bearing materials under lubrication

The aluminium-based alloys, nowadays, are developed to be used in high performance engine bearings. In this study, new Al-based bearing alloys, which are produced by metal mould casting, were developed; and tribologic properties of these alloys under lubrication were analyzed experimentally. Four different aluminium alloys were carried out on pin on disc wear tester for that purpose. SAE 1040 steel was used as the disc material in the wear tester. Friction tests were carried out at 0.231–1.036 N/mm² pressures and at 0.6–2.4 m/s sliding speeds. Wear tests were carried out at 1.8 m/s sliding speed and at 70 N normal load. Friction coefficients and weight losses of the samples were determined under various working conditions as a result of the experiments. The morphographies of the worn surfaces were analyzed. Hardness, surface roughness, and surface temperature of the samples were measured. The results showed that the friction and wear behaviors of the alloys have changed according to the sliding conditions. The effects of the elements except aluminium composing alloys on the tribologic properties were analyzed. Al8.5Si3.5Cu alloy has a lower friction coefficient value than other alloys. Al8.5Si3.5Cu and Al15Sn5Cu3Si alloys, on the other hand, have the highest wear resistance. Al15Pb3.7Cu1.5Si1.1Fe alloy is the most worn material; and Al15Pb3.7Cu1.5Si1.1Fe alloy has the highest wear rate. As a result of the evaluations conducted, Al–Sn and Al–Si alloys, which include Si and Sn, can be preferred, among the aluminium alloys that will work under lubrication, as the bearing material.     

Low cycle fatigue behavior of Ti6Al4V thermochemically nitrided for its use in hip prostheses

Titanium and its alloys have many attractive properties including high specific strength, low density, and excellent corrosion resistance. Besides, titanium and the Ti6Al4V alloy have long been recognized as materials with high biocompatibility. These properties have led to the use of these materials in biomedical applications. Despite these advantages, the lack of good wear resistance makes difficult the use of titanium and Ti6Al4V in some biomedical applications, like articulating components of prostheses. Some surface treatments are available in order to correct these problems, like thermal surface treatment by means of nitrogen gaseous diffusion at high temperature. Nitrogen enters into the material by diffusion, creating a surface layer of increased hardness. Low cycle fatigue behavior in air of Ti6Al4V alloy has been studied. Results show a reduction of low cycle fatigue life up to 10% compared to the not-treated material. Studies suggest it is not related to the titanium nitride surface layer, but to microstructural changes caused by the high temperature treatment.     

Effect of Aging Treatment on Microstructural and Mechanical Characteristics of PEO Coatings on Mg-Al Alloy

Cast Mg-6 wt pct Al alloy solution-treated at 683 K for 16 h and aged at 498 K was coated by plasma electrolytic oxidation （PEO） method.The Mg-6 wt pct Al alloy aged for 16 h exhibited the highest microhardness and wear resistance.After PEO coating,however,the microhardness and wear resistance of coatings on Mg- 6 wt pct Al alloy showed a tendency to decrease with increasing aging time,which was in aggrement with the change of thickness with aging time.In addition,the coatings on solution-treated Mg-6 wt pct Al alloy had better microhardness and wear resistance than those on aged Mg-6 wt pct Al alloys.Consequently,it can be understood that the aging treatment has a deleterious influence on the mechanical properties of coatings on Mg-6 wt pct Al alloy.     

TIC/7075铝基复合材料的磨损实验研究

采用原位反应喷射沉积法制备TiC/7075铝基复合材料,并在销一盘式磨损机损上进行摩擦磨损实验研究.通过TEM观察原位TiC颗粒的分布与形貌,并利用SEM观察沉积态组织磨损表面形貌.结果表明:复合材料的耐磨性和TiC颗粒含量及载荷有关,在低载荷(8.9N)状态下,材料的耐磨性随TiC颗粒含量的增加而增强,在高载荷(26...     

Al含量对CrFeNiAlxSi系高熵合金性能的影响

选取与天然铬铁矿粉有效成分相近的Al、Cr、Fe、Ni、Si元素为高熵合金成分,采用激光烧结技术制备CrFeNiAl_xSi系高熵合金,研究了Al含量对CrFeNiAl_xSi系高熵合金的物相结构、显微组织、密度和孔隙率、显微硬度、耐磨和抗高温氧化性能的影响。结果表明：CrFeNiAl_xSi(x=0.2、0.4、0.6、0.8、1.0)系高熵合金由BCC+FCC相构成,随着Al含量的提高FCC相减少;x=0.6的合金硬度最高,为813.3HV;合金的密度降低孔隙率提高,x=0.2的合金密度最大,为4.21 g·cm^-³,孔隙率最低,为26.46%;x=0.6的合金耐磨性能最佳,磨损率为69.50 mg·cm^-²;随着Al含量的提高,合金的抗高温氧化性能明显提高。     

铝硅合金、铁基粉末冶金、灰口铸铁耐磨性对比

选用压铸铝硅合金、铁基粉末冶金、灰口铸铁进行摩擦对比试验。结果表明,在给定的滑动摩擦条件下压铸铝硅合金的耐磨性最高,加工硬化能力最强;铁基粉末冶金仅次于压铸铝硅合金;灰口铸铁的耐磨必琢加工硬化能力最差。