Advanced Materials Research Vols. 311-313

Abstract: The solution redistribution was an important phenomenon during the solidification of multi-component alloys. The improvements of the solute redistribution were considered in this paper especial in the simulation processes. The models of Gibbs free energy were taken into three kinds such as pure materials, the substitutional solution and the sublattice. Calculating the Gibbs free energy of the system, the solute redistribution coefficients could be calculated. The simulated results of Al-Cu binary and Al-Si-Mg ternary alloys agree well with the experimental results.

Abstract: Based on Empirical Electron Theory in solid (EET) and Bond Length Difference (BLD) the valence electron structures of precipitates in AlCu alloy during aging process were calculated. The results show that the different phase structure factors explain the thermal stability of phases in θ sequence, and the tendency of atoms solution is corresponding with the phase transition during aging from valence electron structure levels, which reveals the inside causes of ageing hardening is closely related to the covalent electron pairs in some bond of the precipitations and matrix.

Abstract: The thermal expansion and the Curie temperature of Tm₂Fe₁₅SiCr compound have been investigated by means of x-ray diffraction and magnetization measurements. The result shows that the Tm₂Fe₁₅SiCr compound has a hexagonal Th₂Ni₁₇-type structure. One Cr and one Si atoms substituting for two Fe atoms can increase the Curie temperature obviously. In magnetic state, an anisotropic anomalous thermal expansion was observed. Along the c-axis, the average linear thermal expansion coefficient αc=-2.04×10^-5/K in the temperature range 303-460K. Along the a-axis, the average linear thermal expansion coefficient αa=-8.09×10^-5/K in 370-410K. In the temperature range 370-450K, the average volume thermal expansion coefficient αv =-2.08×10^-5/K. The mechanism of the thermal expansion anomaly of Tm2Fe15SiCr compound was discussed in this paper.

Abstract: In this paper, the output data of MEMS gyroscope ADRX150 under different input angular velocity within the temperature range of -30°C~50°C is collected and analyzed. Taking the nonlinear and random characteristics of the output data of MEMS gyroscope ADRX150 into account, the dynamic output data model based on RBF neural network is established, which is training and taking the performance testing with the experimental data collection. The results indicate that, the model has high accuracy and good generalization ability.

Abstract: Microstructures, mechanical and creep properties of as-cast and as-annealed Mg-4Al-2Sr-1Ca (AJX421) alloy were investigated. The as cast microstructures of the alloy consists of the α-Mg, lamellar eutectic Mg2Ca and bulky Mg-Al-Sr phase. After annealing at 400°C, lamellar eutectic tended to be spheroidised and the continuous interphase network breaks up gradually, meanwhile, C14-Mg₂Ca completely transforms to C15-Al₂Ca. These results in obvious decrease of creep property. It is proposed that the continuous network distribution of compounds paly a major role in restricting the creep deformation of Mg-Al alloy at elevated temperatures, and the grain boundary sliding is an important creep mechanism for the alloy studied.

Abstract: 1Cr18Ni9Ti specimens were observed the plastic deformation by the method of coordinate grid under the low stress repeated impact test. And it found some phenomenon is similar to the creep phenomenon ,so the paper call it “repeated impact creep”. Proceeding from the theory of creep deformation, the deformation law of the specimens was analyzed and the relevant mathematical model was established.Finally, it found that the strain rate of repeated impact creep is decreased by the increase of impact times and the increase of layer’s depth.

Abstract: New metastable beta titanium alloy Ti-4Al-2.7V-12Mo-10Nb-1Zr-0.2Cr was carried out in the arc melting vacuum furnace. The microstructure and mechanical properties of a new metastable beta titanium alloy Ti-4Al-2.7V-12Mo-10Nb-1Zr-0.2Cr were compared at different aging temperature and time. The growth mechanism of α phase is analysed by comparing the morphology of the precipitated phase at different temperature. Test results indicate that titanium alloy Ti-4Al-2.7V-12Mo-10Nb-1Zr-0.2Cr has the best property through two-step aging treatment. The tensile strength of titanium alloy Ti-4Al-2.7V-12Mo-10Nb-1Zr-0.2Cr after final aging treatment achieves 1180MPa with 8% elongation trough tensile test. The strengthing mechanism was also discussed in this paper.

Abstract: The connection design of flow path is the most important task in Hydraulic Manifold Blocks (HMB) design. But the traditional method of feature design can not dynamically change the topology configuration and parameters of flow path when the design changed. This paper use a hybrid model consisting of temporary body model and B-Rep model, and represent flow path pattern using adjacency graph, adjacency matrix, weight matrix and degree array. The design parameters can be optimized by non-dominated sorting genetic algorithm (NSGA2). The topology configuration of flow path can adaptively change according to the design change.

Abstract: Supersaturated Mg-Gd-Y alloy followed by aging at 225 °C with different times were subjected to quais-static and dynamic strain rates to determine the influence of precipitate phase β′ on the strain rate sensitivity of magnesium alloy. Strain rate sensitivity (SRS) decreases with the increase of the size of β′. SRS decreases from initial condition to peak-aged condition due to the β′ increases the athermal component of flow stress. On the other hand, the influence of precipitate interfaces on dislocation generation and storage mechanisms may be responsible for the decrease of SRS from peak-aged to over-aged condition.

Abstract: Ni(Ⅱ) was reduced to Ni atom irreversibly by a one-step reaction in acetamide-urea-NaBr melt at 353K. The electron-transfer coefficient, and the diffusion coefficient, D₀ were determined to be 0.21 and 1.15×10^-8 cm².s^-1 on Pt electrode. Although the Ce（Ⅲ）and the Mg（Ⅱ）cannot be reduced to Ce and Mg alone, they can be inductively codeposited with Ni（Ⅱ）to obtain an amorphous Ce-Mg-Ni alloy film by potentiostatic electrolysis. The content of Ce in the alloy increase with the increasing of the molar ratio of Ce（Ⅲ）/Ni（Ⅱ） and reaches to the maximum of 49.70 wt%. The content of Mg in the alloy increase with the increasing of the cathode potential and the maximum was 4.558wt%.