Al/Fe bimetals prepared by a compound casting method, combining the excellent properties of both the Al alloy and the ductile cast iron, exhibit great potential for application in achieving engine weight reduction. However, the problem of insufficient interfacial bonding ability because of the difference in thermophysical properties of Al and Fe is particularly prominent. Therefore, in this work, the electrodeposited Cu coating on the surface of the Fe matrix was used as the interlayer of Al/Fe bimetal fabricated by coupling hot-dipping with compound casting to solve the above problem. The effect of Cu interlayer thickness on the interfacial microstructure and shear strength of bimetal was investigated. The experimental results showed that the shear strength up to 77.65 MPa in regard to Al/Fe bimetal with a 5 μm Cu interlayer was obtained. No Cu element was detected at the interface of bimetal regardless of the thickness of the Cu interlayer. The diffusion behavior of the Cu atom at the interface and the influence of the Cu layer at the atomic scale on diffusion reaction and the Al/Fe interface were further revealed by combining first-principle and molecular dynamics calculations. The simulation results revealed that the Cu layer gradually dissolved into an Al alloy at 750 °C, thereby promoting the diffusion reaction of the Al/Fe interface. Meanwhile, the protective role of the Cu layer against oxidation on the surface of the Fe matrix was confirmed. As a result, the interfacial bonding performance was enhanced when the Cu interlayer was introduced.
Rotating backward extrusion (RBE) is one of severe plastic deformation (SPD) methods used to produce cylindrical components with a very large strain by a single pass. In this study, the microstructure and texture evolution in the different regions of Mg-12Gd-4Y-2Zn-0.5Zr (wt.%) alloys via RBE process were investigated by using optical microscopy (OM), X-ray diffraction (XRD), scanning electron microscopy (SEM) and electron back-scatter diffraction (EBSD). The results showed that the cup-shaped sample formed by RBE process exhibited typical gradient microstructure expanding from its inner wall to outer wall along the radial direction (RD). The average grain size of the RBEed sample decreased when the radius decreased from the edge region to the center region along the RD, which was attributed to the different strains and strain rates in the different regions. It also could be observed that the center region showed highest deformation and the edge region exhibited the lowest deformation in the RBEed sample along the RD. In addition, the grain refinement mechanisms of the experimental alloy containing long-period stacking ordered (LPSO) phases after RBE with 100 N were continuous dynamic recrystallization (CDRX), discontinuous dynamic recrystallization (DDRX) and particle stimulated nucleation (PSN).
1 September 2011 in Journal of Nanoscience and Nanotechnology
Chiral Zn(II)/D-,L-phenylalanine (Phe) bio-coordination polymer nanofibers with fluorescence were prepared by fast coordination-assisted assembly. The synthetic strategy is based on the fact that the Zn2+ ions were linked to oxygen atoms from carboxylate groups of the D- or L-amino acid by coordination interactions to form the chiral polymers. The Zn(II)/D-,L-Phe nanofibers had homogeneous diameters in the range of 700∼900 nm and ultra-long length in several hundred micrometers, and the surface of the fiber was extremely smooth. In addition, the enantiomers of Zn(II)/Phe nanofibers exhibited both optical activity and fluorescent property in the solid state, which has great potential for application in the field of biomimetic nanofabrication and micro-/nano-optoelectronics.
1 February 2022 in Journal of Physics: Conference Series
Titanium diboride has a series of excellent physical and chemical properties, high melting point and hardness, good thermal stability and oxidation resistance. As an excellent hard phase, titanium diboride is used in new materials such as composite materials and cermet. It has a wide prospect in the application of high-temperature ceramics. In this paper, the research status, performance structure, preparation method and application of titanium boride high-temperature ceramics are analyzed and summarized from the overall point of view, and the main problems faced by titanium boride at present are also discussed. Finally, the future research direction of titanium boride high temperature ceramics is discussed.
1 June 2021 in Journal of Physics: Conference Series
Through controlling from the source, TC4 titanium alloy profile ingot heating process surface protection technology and extrusion lubrication process, extrusion die design and manufacturing, profile straightening process, finished product heat treatment process and profile hot bending forming and other key processes have been studied in depth. Technical improvements and quality assurance measures are proposed. The surface quality, shape, size and mechanical properties of the titanium alloy profile meet the requirements of the use of TC4 titanium alloy profile parts for a certain type of launch vehicle. Ensure that the TC4 titanium alloy profile acceptance inspection process is operable. The manufacturing cost of the titanium alloy outer stringer of the launch vehicle is reduced. The quality level and reliability of TC4 titanium alloy outer stringers have been improved.