A preliminary study on optimizing the heat treatment of high strength Al–Cu–Mg–Zn alloys

The design of critical aerospace alloys is primarily built on optimizing strength and ductility, both of which can be enhanced by controlling the alloying element additions as well as heat treatment conditions. The 7075 alloy is one such aerospace alloy. The main objective of this study was to optimize the 7075 strength. Several experimental alloys were prepared and tensile test bars were cast using an ASTM B-108 type permanent metallic mold. The as-cast samples were then solution heat-treated at 470 °C for times up to 48 h. The solution heat-treated bars were also aged in order to improve the alloy strength through precipitation hardening. Line scans for Mg, Cu and Zn were obtained from the various heat-treated alloy samples using an electron probe microanalyzer equipped with Energy Dispersive X-ray (EDX) and Wavelength Dispersive Spectroscopic (WDS) facilities. Peaks corresponding to the Mg, Cu and Zn concentrations in the as-cast samples disappeared after solution treatment, reflecting optimized homogeneity structures. The newly developed versions of the 7075 alloy displayed an ultimate tensile strength (UTS) of ∼1 GPa.     

Study on effects of pre-treatment and surface roughness on tensile-shear strength of 2060 Al–Li alloy adhesive joints

The forces between adhesive and adherend mainly influenced by the pre-treatment technology of the substrates have important effects on the bonding strength. In this paper, the influence of different pre-treatment processes and surface roughness on the tensile-shear strength of 2060 Al–Li alloy adhesive joints as well as related mechanism was investigated. In this perspective, substrates were processed by mechanical abrasion at different levels and by phosphoric acid anodizing, which resulted in different surface topographies that were characterized by means of roughness measurements. Single-lap joints were prepared using a two-component epoxy adhesive. The tensile-shear strength of joints was measured via destructive testing and the failure modes were analyzed to evaluate the quality of bonding. Results showed that with the increase of surface roughness of Al–Li alloy, the tensile-shear strength of the adhesive joints increased and the failure modes changed from interfacial failure to cohesive failure. The groove structures formed during mechanical abrading were regarded as being responsible for this strengthening behavior. Moreover, a rough porous membrane was produced on adherents’ surface by phosphoric acid anodizing, causing a consolidation of adhesion at the adhesive-substrate interface.     

Effects of aluminium nitride silane-treatment on the mechanical and thermal properties of polybenzoxazine matrix

A new kind of polymer composite, produced from the typical polybenzoxazine and 0–30 wt-% native and silane-treated aluminium nitride (T-AlN), was investigated. The mechanical tests revealed a significant increase in the microhardness and flexural properties upon adding the T-AlN particles compared to that obtained from the untreated ones. By adding 0–30 wt-% T-AlN, the tensile moduli were accurately reproduced by the Halpin-Tsai and Nielsen models. At 30 wt-% T-AlN, dynamic mechanical analysis showed a significant increase in the storage moduli and the glass transition temperature (T_g), reaching 3.2?GPa and 217°C, respectively. The thermal stability of these materials was significantly improved upon the addition of the T-AlN fillers. These improvements are attributed to the high thermal and mechanical properties of the fillers and their good dispersion and adhesion in and to the matrix as revealed by a morphological analysis.     

The light alloy Calphad databases PanAl and PanMg

Thermodynamic databases for multi-component aluminum alloys, PanAl, and magnesium alloys, PanMg, are reviewed and applications are highlighted. Precipitation simulations by combining thermodynamic and mobility databases for Al and Mg alloys with the PanPrecipitation module of Pandat are also demonstrated. These simulations can serve as virtual experiments to understand the effects of alloy composition and heat treatment condition on the target properties therefore provide guidance for the design of real experiments, save time and reduce cost. For PanAl the focus in this work is on 7xxx alloy and high throughput calculation (HTC) to understand/predict the effects of major and minor alloying elements on the selected properties of an alloy. For PanMg applications are exemplified in a wider spectrum of Mg alloy design and related processing parameters and the usefulness of the CALPHAD modeling tool in Mg technology is demonstrated.     

Quantitative study of the kinetics of hydrogen evolution reaction on aluminum surface and the influence of chloride ion

The behaviors and kinetics of hydrogen evolution reaction (HER) on pure aluminum with passive film in the presence and absence of chloride ion are quantitatively investigated by using the tip generation/substrate collection mode of scanning electrochemical microscopy (SECM) with dual Al/Pt ultramicroelectrode (UME) as tip electrode and Pt UME as substrate electrode. The standard rate constants k⁰ and transfer coefficients α_H of HER in ClO₄⁻- and Cl⁻-containing solution are 6.9 × 10⁻⁷ cm/s and 0.22, 7.1 × 10⁻⁶ cm/s and 0.19, respectively. Results show that the kinetic of HER is slow and the destruction of Cl⁻ on passive film can significantly promote the HER on Al surface. Moreover, these α_H far less than commonly used 0.5 in corrosion research, can explain the great difference between theoretical Tafel slopes and experimental results. Besides, the existence of current plateau in Al electrode explains the large difference in corrosion potential during parallel testing.     

Differential elastic scattering cross sections of protons from Al in 2.4–4.8 MeV energy range

Measurement of differential elastic cross section of protons from aluminum was taken at 165° degree in the2.4–4.8 Me V energy range. The results and measured energy resonances were compared with reported measurements.These data will improve the reliability of backscattering analysis of Al with protons in this energy region.     

Research on distribution of aluminum in electron beam melted silicon ingot

The purification of metallurgical grade silicon, especially the removal of aluminum, was investigated by electron beam melting and solidification. Small amounts of silicon raw materials were melted in an electron beam furnace with same melting time and different solidification time to obtain the distribution of Al in silicon ingot. The removal mechanisms in different stages were also discussed. The results show that the removal of Al during melting process only depends on evaporation and that during solidification process depends on both segregation and evaporation. The distribution of Al shows an obvious increasing trend from the bottom to the top of the silicon ingot when solidification time is 600 s. The removal efficiency in most area is close to that in the ingot solidified instantaneously, but the energy consumption is less, which is considered to be an effective way for the purification of silicon.     

双动铝挤压机液压定针控制技术

介绍了双动卧式铝挤压机液压定针系统的结构、工艺流程及其自动控制系统。该控制系统响应快,定针精度高,具有很高的可靠性。目前该液压定针控制系统已应用于实际生产,定针控制精度≤1mm,完全满足工艺要求,对后续同类产品的设计起到了借鉴作用。     

铝合金在自行车上的应用

本文介绍铝合金在交通运输方面尤其在自行车、电动车等方面的应用和发展,并指出自行车这一传统工具在国内某些城市的新用途,成为城市低碳出行的最佳选择之一,间接地为城市交通的发展提供一种节能、环保和惠民的新思路。