0.1wt% Boron addition Effect on dynamic compressive mechanical properties of Ti-6Al-4V alloy

0.1wt% Boron addition effect on dynamic compression properties of Ti-6Al-4V (Ti-64A) alloy are investigated by Split Hopkinson Pressure Bar (SHPB). In the study, and relative damage mechanism is also analyzed. The results show that, as-cast microstructure is refined due to 0.1% Boron addition and also to lower the non-uniform distribution of strain, stress or local concentration due to inharmonic deformation. As well as both dynamic strain and average dynamic flow stress is improved with a reduction of the sensitivity of adiabatic shear behavior. As deformation microstructure loaded at high strain rate with 0.1wt% boron addition, Dynamic strain and maximum absorbed energy is decrease 10%~30% compare with Ti-64A alloy. Both Ti-64A and Ti-6Al-4V-0.1B (Ti-64B), average dynamic flow stress is close. At high speed impact load, it exhibits a damage of adiabatic shear and TiB phases bear loading during fracture. Adiabatic shear band ismain reason of Ti-64A and Ti-64B alloys fracture failure through the deformed specimens’ microstructure observation. Adiabatic shear band formation and expansion is a precursor of material shear fracture failure. Deformation cavity can be formation between TiB phase and matrix during the deformation process, but not the main reason of material fracture failure

0.1wt% Boron addition Effect on dynamic compressive mechanical properties of Ti-6Al-4V alloy

0.1wt% Boron addition effect on dynamic compression properties of Ti-6Al-4V (Ti-64A) alloy are investigated by Split Hopkinson Pressure Bar (SHPB). In the study, and relative damage mechanism is also analyzed. The results show that, as-cast microstructure is refined due to 0.1% Boron addition and also to lower the non-uniform distribution of strain, stress or local concentration due to inharmonic deformation. As well as both dynamic strain and average dynamic flow stress is improved with a reduction of the sensitivity of adiabatic shear behavior. As deformation microstructure loaded at high strain rate with 0.1wt% boron addition, Dynamic strain and maximum absorbed energy is decrease 10%~30% compare with Ti-64A alloy. Both Ti-64A and Ti-6Al-4V-0.1B (Ti-64B), average dynamic flow stress is close. At high speed impact load, it exhibits a damage of adiabatic shear and TiB phases bear loading during fracture. Adiabatic shear band ismain reason of Ti-64A and Ti-64B alloys fracture failure through the deformed specimens’ microstructure observation. Adiabatic shear band formation and expansion is a precursor of material shear fracture failure. Deformation cavity can be formation between TiB phase and matrix during the deformation process, but not the main reason of material fracture failure

Effect of Ni/Si Mass Ratio and Thermomechanical Treatment on the Microstructure and Properties of Cu-Ni-Si Alloys

The effect of the Ni/Si mass ratio and combined thermomechanical treatment on the microstructure and properties of ternary Cu-Ni-Si alloys is discussed systematically. The Cu-Ni-Si alloy with a Ni/Si mass ratio of 4–5 showed good comprehensive properties. Precipitates with disc-like shapes were confirmed as the Ni2Si phase with orthorhombic structure through transmission electron microscopy, high-resolution transmission electron microscopy, and 3D atom probe characterization. After the appropriate thermomechanical treatment, the studied alloy with a Ni/Si mass ratio of 4.2 exhibited excellent mechanical properties: a hardness of 290 HV, tensile strength of 855 MPa, yield strength of 782 MPa, and elongation of 4.5%. Compared with other approaches, the thermomechanical treatment increased the hardness and strength without sacrificing electrical conductivity. Theoretical calculations indicated that the high strength was primarily attributed to the Orowan precipitation strengthening and secondarily ascribed to the work hardening, which were highly consistent with the experimental results. The appropriate Ni/Si mass ratio with a low content of Ni and Si atoms shows high strength and excellent electrical conductivity through combined thermomechanical treatment. This work provides a guideline for the design and preparation of multicomponent Cu-Ni-Si-X alloys with ultrahigh strength and excellent electrical conductivity

Effect of Cold Working on the Properties and Microstructure of Cu-3.5 wt% Ti Alloy

Cu-Ti alloys were strengthened by β’-Cu4Ti metastable precipitation during aging. With the extension of the aging time, the β’-Cu4Ti metastable phase transformed into the equilibrium β-Cu4Ti phase. The Cu-3.5 wt% Ti(Cu-4.6 at% Ti) alloys with different processing were aged at different temperatures for various times after solution treatment at 880 °C for 1 h. The electrical conductivity of samples under different heat treatments had shown an upward trend as time increased during aging, but the hardness reached the peak value and then decreased. The hardness and electrical conductivity of the samples with 70% deformation after aging are higher tha n the samples without deformation. Deformation after aging would cause the metastable phase to dissolve into a matrix. The best combination value of conductivity and hardness is 13.88% IACS and 340.78 Hv, and the optimal heat treatment is 500 °C for 2 h + 70% deformation + 450 °C for 2 h

Effect of Annealing on the Interface and Properties of Pd/Al Composite Wires

This paper investigates the changes in the interface organization and properties of 0.10 mm Pd/Al composite wires annealed at different temperatures. The optimum comprehensive performance of the material was obtained after annealing at 300 °C for 120 s. Its tensile strength, conductivity and elongation are 140.61 MPa, 46.82%IACS and 14.89%, respectively. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to observe the intermetallic compounds on the interface. The annealing temperature and the formation heat of intermetallic compounds determine the categories and evolution of intermetallic compounds. When the thickness of the intermetallic layer is more than 1 μm, it has a serious effect on the electrical conductivity and elongation of the materials

Analysis of microstructures and XRD of a gradient boron alloyed composite material

A new type of gradient boron alloyed composite material, containing boron alloyed core layers and stainless steel coatings around the core, were designed and prepared by composite casting and hot rolling. The evolution of microstructures, phases and precipitations, as well as their influence on hot rolling process and performance are investigated. A mixture of austenitic matrix and uniformly distributed borides are obtained in the hot rolled stainless steel with 2-2.5 % boron, while massive borides are in the length of 80-120 μm together with micro gaps at the interface between the borides, and the matrix is remained after hot rolling for the core layers with higher boron contents. Hot deformation would be hindered since more precipitations of these orthorhombic or tetragonal phases occur with an increase of the boron concentration in the core layers. © (2013) Trans Tech Publications, Switzerland

Preparation and properties of 3D interconnected CNTs/Cu composites

In this paper, the 3D pore structure of CuCr powders were obtained by pre-press shaping process, and finally the 3D interconnected carbon nanotubes/copper (CNTs/Cu) composites with excellent properties were insitu synthesized by chemical vapor deposition (CVD) and spark plasma sintering (SPS) technique. The morphology and structure of CNTs/ Cu composites are characterized by scanning electron microscopy (SEM), Raman spectra, transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), and the results showed that the quality of CNTs and the interfacial bonding strength of CNTs/ Cu composites can be improved owing to the 3D pore structure. Meanwhile, the 3D pore structure was favorable to avoid pollution of CNTs during the synthesis process. The tensile strength of CNTs/ Cu composites increased to 421.2 MPa, with 47.6% enhancements compared to CuCr. Furthermore, the coefficient of friction (COF) reduced to 0.22 and the corrosion resistance were increased by 51.86% compared to CuCr. Consequently, our research provides a novel and an effective method for the synthesis of high quality CNTs/ Cu composites

Comparative study on the properties and microscopic mechanism of Ti coating and W coating diamond-copper composites

Interface plays a decisive role in metal matrix composites, and the effects of Ti coating and W coating on the properties and microscopic mechanism of diamond-copper composites are compared in this paper. Ti-coated diamond with 50 nm, 100 nm and 150 nm plating thickness and W-coated diamond with 50 nm plating thickness are prepared by using magnetron sputtering. Then infiltration method is carried out to prepare diamond copper composites. SEM, EDS and XRD are used to material microstructure. Three-point bending experiment and flash method are used to test the bending strength and thermal conductivity of the composite material. The study found that, as the thickness of the Ti coating increases, the bending strength of the composites gradually increases, but the thermal conductivity first increases and then decreases. The thermal conductivity of W coated diamond copper composites is higher than that of Ti coated diamond copper composites with the same coating thickness. But bonding strength shows the opposite law. The reason for the above phenomenon is that the mechanism of action between the Ti coating and the W coating and the copper substrate is different at the micro interface of the composites. The research work has important reference value for the interface modification of diamond copper composites

Effect of Sn Addition on Microstructure, Aging Properties and Softening Resistance of Cu-Cr Alloy

The relationship between microstructure evolution and properties of a Cu-Cr-Sn alloy during aging and high-temperature softening was investigated in detail in the present work. The results show that the addition of Sn refines obviously the size of the Cr phase and enhances the thermal stability of the alloy, which improves the peak-aged hardness of the Cu-Cr-Sn alloy reaching 139 HV after aging at 450 °C for 240 min. In addition, the recrystallization behavior of the Cu-Cr alloy with the 0.12 wt.% of Sn at high temperature is also significantly inhibited. Lots of precipitated Cr phases and a high density of dislocations are found in the Cu-Cr-Sn alloy annealed at high temperature, resulting in the softening temperature of the Cu-Cr-Sn alloy reaching 565 °C, which is higher than (about 50 °C) that of the Cu-Cr alloy