Reactivity of Al-rich Alloys with Water Promoted by Liquid Al Grain Boundary Phases

Al–Ga–Sn, Al–Ga–In and Al–Ga–In–Sn alloys were prepared using arc melting technique. Their microstructures were investigated by X-ray diffraction and scanning electron microscopy with energy dispersed X-ray. Based on microstructure analysis, the phase constituents of alloys at Al grain boundaries were identified. The melting points of Al grain boundary phases were measured using differential scanning calorimeter.The reactivities of Al–water at different water temperatures indicate that liquid Al grain boundary phases promote Al–water reactions of alloys. The melting points of Al grain boundary phases affect the reaction temperatures of Al–water, leading to different reaction temperatures of alloys. The measured H2 generation rate and yields of alloys are related to the compositions of alloys. The theory of microgalvanic cell is used to explain the observed different H2 generation rates of alloys.

Thermal decomposition kinetics of titanium hydride and Al alloy melt foaming process

A temperature programmed decomposition (TPD) apparatus with metal tube struc- ture, in which Ar is used as the carrier gas, is established and the TPD spectrum of titanium hy- dride is acquired. Using consulting table method (CTM), spectrum superposition method (SSM) and differential spectrum technique, TPD spectrum of titanium hydride is separated and a set of thermal decomposition kinetics equations are acquired. According to these equations, the rela- tionship between decomposition quantity and time for titanium hydride at the temperature of 940 K is obtained and the result well coincides with the Al alloy melt foaming process.

Segregation Behavior and Evolution Mechanism of Iron-Rich Phases in Molten Magnesium Alloys

A new method has been proposed to prepare Mg-A1-Si master alloys by utilizing scrap AI-Si-Fe alloys with higher Fe levels, which aims to segregate Fe from AI-Si-Fe alloys by Mg melt. The segregation be- haviors, microstructure morphology and evolution mechanism of iron-rich phases in Mg-A1-Si alloy melts were studied, after AI-14Si-4Fe （wt%） alloys were added and dissolved completely. In the Mg-A1-Si alloys, iron has very little solubility and tends to combine with other elements to form intermetallic phases, which grow into a deposition layer due to the higher density. During the cooling and solidifying process of Mg-A1-Si melts, the needle-like AlsSiFe phase in AI-14Si-4Fe alloy evolved into blocky AI5Fe2 and Al0.7Fe3Si0.3 phases. Besides, the Fe levels of the Mg-AI-Si master alloys were reduced to 0.017 wt% from nominal content of 0.164 wt%. Based on the above results, this work carried out a semi-quantitative phase- compositions analysis for the deposition layer by relative intensity ratio （RIR） method, and evolution mechanism of the iron-rich phases had also been discussed. This study has paved a new way to regen- erate the scrap AI-Si-Fe alloys, which has a great significance of promoting the recycling of aluminum resources.

Microstructural Characterization and Mechanical Properties of VB_2/A390 Composite Alloy

In this work, we make the best use of the vanadium element; a series of A1-V-B alloys and VB2/A390 composite alloys were fabricated. For Ak-10V-6B alloy, the grain size of VB2 can be controlled within about 1 μm and is distributed uniformly in the AI matrix. Further, it can be found that VB2 promises to be a useful reinforcement particle for piston alloy. The addition of VB2 can improve the mechanical properties of the A390 composite alloys significantly. The results show that with 1 % VB2 addition, A390 composite alloy exhibits the best performance. Compared with the A390 alloy, the coefficient of thermal expansion is 13.2 × 10^-6 K-1, which decreased by 12.6%; the average Brinell hardness can reach 156.5 HB, wear weight loss decreased by 28.9% and ultimate tensile strength at 25℃ （UTS25 ℃） can reach 355 MPa, which increased by 36.5%.