The Enhanced Effect of Optical Emission from Laser Induced Breakdown Spectroscopy of an Al-Li Alloy in the Presence of Magnetic Field Confinement

In this paper, the influence of magnetic field strength on laser-induced breakdown spectroscopy （LIBS） has been investigated for various pressures. The plasma plume was produced by employing Q-switch Nd：YAG laser ablation of an A1-Li alloy operating at a 1064 nm wavelength. The results indicated that the LIBS intensity of the A1 and Li emission lines is boosted with an increase of magnetic strength. Typically, the intensity of the A11 and Li I spectral emissions can be magnified by 1.5-3 times in a steady magnetic field of 1.1 T compared with the field-free case. Also, in this investigation we recorded time-resolved images of the laser-produced plume by employing a fast ICCD camera. The results show that the luminance of the plasma is enhanced and the time of persistence is increased significantly, and the plasma plume splits into two lobes in the presence of a magnetic field. The probable reason for the enhancement is the magnetic confinement effect which increases the number density of excited atoms and the population of species in a high energy state. In addition, the electron temperature and density are also augmented by the magnetic field compared to the field-free case.

EFFECT OF Cu ON MICROSTRUCTURE AND PROPERTIES OF Al-Li ALLOYS

The aging precipitation structure and the properties of Al-Li-Cu-Zr alloys with 3 different Cu/Li ratios have been studied.Experimental results show that the aging hardening of the alloys consists of two steps:The first is strengthened by δ′-phase(δ′+T_1 phase in alloy No.3),and the second by δ′+T_1 phase(δ′+T_1+θ′phase in alloy No.3).The plate of T_1-phase can absorb the Li atoms from δ′ particles when the plate bumped into δ′-phase,and therefore, these δ′ phase particles become smaller and gradually disappear.The strength and hardness increase with the increase of Cu/Li ratio and cuases a decrease in plasticity.The crack mode would change from transgranular to intergranular.This is due to the precipitation of the equi- librium phases contained Cu at grain boundaries.

Composition and corrosion resistance of cerium conversion films on 2195Al-Li alloy

The Ce conversion films on 2195A1-Li alloy without and with post-treatment were studied and the corrosion resistance was evaluated as well. The surface morphology was observed by scanning electron microscopy （SEM）, and the chemical composition was characterized by X-ray photoelectron spectroscopy （XPS）. The corrosion behaviors of 2195A1-Li alloy and conversion coating were assessed by means of potentiodynamic polarization curves. The experimental results indicated that after post-treatment the surface quality was improved significantly. According to XPS, the conversion coating after post-treatment was mainly composed of CeO2, Ce203, Ce-OH and a little MoO3 and MOO2. The results of potentiodynamic polarization curves revealed that the conversion coating with post-treatment possessed better corrosion resistance than bare alloy and Ce conversion coating without post-treatment.

MICROSTRUCTURE-PROPERTY RELATIONSHIP OF Al-2.2Li-2.5Cu-0.2Mg ALLOY

The relationship among the microstructures,properties and the phase transformation in Al-2.2Li-2.5Cu-0.2Mg alloy after various treatments have been studied by optical microscopy and TEM observations.It is verified that solution treated at 525℃ for 1h is saris- factory for this alloy in which all the alloying elements are dissolved in the α-Al matrix,and aging at 190℃ for 16 h is the peak-aged condition.The alloy subjected to treatment is strengthened only be T_1 phase.In overaged or underaged conditions,the alloy is strengthened by two phases,in this cases,the strengthening effect is smaller than that by one phase.The deformation prior to aging would develop the plasticity and do not decrease the strength of the experimental alloy.

Electrochemical Formation of AI-Li Alloys by Codeposition of AI and Li from LiCI-KCI-AIF3 Melts at 853 K

The electrochemical behavior of AI（III） ions was studied in molten LiC1-KC1 melts on a molybdenum electrode. Cyclic voltammetry, chronopotentiometry and chronoamperometry were used to explore the deposition mechanism of A1 and Li. Cyclic voltammetry expriment indicates that under potential deposition（UPD） of lithium on pre-deposited aluminium led to the formation of liquid A1-Li alloys at 853 K. The diffusion coefficient of AI（III） ions at 853 K in LiC1-KC1-AIF3（I%, mass fraction） melts was determined to be （2.79~0.05）x 10_5 cm2/s. Chronopotentio- grams and chronoamperograms demonstrate that the codeposition of AI（III） and Li（I） ions formed A1-Li alloys at ca- thodic current densities higher than -0.28 A/cm2 or cathodic potentials more negative than -2.20 V. X-Ray diffrac- tion（XRD） pattern indicates that A1-Li alloys with different phases formed via galvanostatic electrolysis. Inductively coupled plasma（ICP） analyses of the samples obtained by electrolysis show that lithium and aluminium contents of A1-Li alloys could be controlled by A1F3 concentration and current intensity.

Homogenization heat treatment of 2099 Al–Li alloy

Abstract The microstructure evolution and composition distribution of as-cast and homogenized 2099 aluminumlithium （Al-Li） alloy were studied by optical microscopy （OM）, differential thermal analysis （DTA）, scanning electron microscopy （SEM）, energy dispersive spectrometry （EDS）, area and line scanning, X-ray diffraction （XRD）, and Vickers microhardness test methods. The results show that severe dendrite exists in the as-cast alloy. Cu, Zn, Mn, and Mg distribute unevenly from the grain boundary to inside. The low-melting point nonequilibrium eutectic phases dis- solve into the matrix during the first-step homogenization, whereas the melting point of residual eutectic phases is elevated. After the second-step homogenization, most of the remaining eutectic phases dissolve into the matrix, except a small amount of A1-Cu-Fe phases. An optimized homogenization process of the 2099 A1-Li alloy is developed （515℃ - 18 h ＋ 525℃ - 16 h）, which shows a good agreement with the homogenization kinetic analysis results.