In this study, the effects of Zr, Zn and Cu additions on the microstructure, room-temperature and high-temperature mechanical properties of an Mg-3Sn-1Ca alloy (from 25 °C to 250 °C) were studied. ...The results reveal that additions of Zr and Zn do not change the phase composition of the alloy, composed of CaMgSn and Mg2Sn phases. After the addition of Zn, the grains are significantly refined, the volume fraction of the second phase is increased and dispersed, and the Mg2Ca phase is precipitated. The grain refinement of Zr is better than that of Zn. After adding the Cu element, the Mg2Cu phase precipitates besides the CaMgSn phase. A comparison of mechanical properties shows that the alloy with Zr (TXK311) has the best mechanical properties at room temperature and high temperature, and the elongation of the TXK311 alloy can reach 68.3 % at 250 °C. The TXK311 alloy was comprehensively considered to find its optimum mechanical properties. The analysis shows that fine grains, a uniform phase distribution and texture play important roles in the deformation of the alloy.
Different cooling rates, such as room temperature water cooling (WQ), furnace cooling (FC), and water cooling + furnace cooling (FC +WQ), were introduced to study the effect on the solution-treated ...Mg-9Gd-4Y-2Zn-0.5Zr (w/%) alloy microstructure and mechanical properties. The grain size decreases as the cooling rate increases. With the lengthening of the cooling process time, the LPSO phase had enough time to nucleate and diffuse, the LPSO (long-period stacking order) phase filled the whole matrix crystal grains at the same time. In the process of furnace cooling and water cooling, the brightness of the LPSO phase was different, so it could be seen that the cooling rate would affect the contrast and morphology of the LPSO phase. The tensile yield strengths of the samples cooled with the furnace were better than those of the water-cooled samples, but their ultimate tensile strength and elongation to failure were poor. The fracture modes of the samples under different cooling rates were all subject to cleavage fracture, and the number and area of the cleavage planes and cleavage steps increased with the decrease of cooling speed, and the tearing area decreased, resulting in poor ultimate tensile strength and stretchability.
To explore the effect of pulse duration on the micro-morphology and mechanical properties of laser-welded glass joints, a glass welding experiment was carried out. The microstructure of the molten ...layer with different pulse durations was shown by field-emission scanning electron microscopy. The pores and distribution characteristics were analyzed, and the porosity variation rule of the welding layer for different pulse durations was obtained. The line-scan analysis of the joint interface was carried out with a D8-Advance type crystal X-ray diffractometer, and the relationship between the thickness of the reactive wetting layer and the pulse duration was obtained. The hardness and welding strength of the laser-welded glass joints were obtained with a Vickers hardness tester and an electronic universal testing machine. This study can provide a theoretical and experimental basis for the laser welding of glass.
This study enhances the strength of the Al6061 alloy by adding Ti in the form of a rod using a thermomechanical process, which would be useful in making structures for aerospace and structural ...members. Two different properties of the material are joined together to form a new bimetallic material. Softer Al-6061 is used as a sleeve, and grade-II Ti is used as a core. They were prepared with a co-extrusion process at a temperature of 400 °C with different ratios of 2:1 and 2:0.5. The prepared substrates are analysed for characterization, hardness, tensile strength, and corrosion. The development of the diffusion layer is observed at the boundary of the Al-Ti material, and the bonding is improved. Compared to an aluminium alloy and a 2:1 bimetal composite, the co-extruded Al-Ti with a ratio of 2:0.5 bimetal composite ratio shows a better microstructure, mechanical, and tribological properties. It is concluded that the co-extrusion of Ti and Al is an efficient way to devise new composites with mechanical properties of 14% and 19%, respectively.
A new refractory alloy, HfMoNbTiCr, was obtained by replacing Zr with Cr or Mo in the HfMoNbTiZr or HfNbTiCrZr alloys using vacuum arc melting. The phase components, microstructures and compressive ...properties of the alloy in the as-cast and annealed states were investigated. The results showed that the phase components changed from a single BCC phase in HfMoNbTiZr and BCC+Laves phases in HfNbTiCrZr to multiple phases – primarily two BCC phases and two cubic Laves phases – in HfMoNbTiCr. Notably, the yield and ultimate compressive strength of the as-cast alloy significantly increased from 1719 and 1803 MPa to 1851 and 2489 MPa, without a decrease in the ductility. The stress fields induced by Mo and the Cr-containing Laves phases were responsible for the enhanced strength, while the stiff network-like framework composed of intrinsically-strong Cr-containing Laves phases may have played a vital role in retaining the ductility.
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