Microstructure and Hardness of AlMg3 Alloy Subjected to Ultrasonic Upsetting

This study was conducted to study the effect ultrasonic vibrations on the evolution of the microstructure and hardness of the AlMg3 aluminum alloy in a solution treated condition. To understand the process physics in this article, after the deformation the microstructures of the samples before and after deformation were analyzed by the light and electron microscopy, including the electron backscatter diffraction (EBSD) analysis. The result evidently shows that the ultrasonic-assisted deformation has a meaningful influence on the grain refinement – the application of the USV enhances the formation of deformation bands and new sub-grains. This resulted in a certain hardness enhancement.

Microstructure Refinement by Low-Temperature Ausforming in an Fe-Based Metastable High-Entropy Alloy

The effects of ausforming in an Fe30Mn10Cr10Co high-entropy alloy on the microstructure, hardness, and plastic anisotropy were investigated. The alloy showed a dual-phase microstructure consisting of face-centered cubic (FCC) austenite and hexagonal close-packed (HCP) martensite in the as-solution-treated condition, and the finish temperature for the reverse transformation was below 200 °C. Therefore, low-temperature ausforming at 200 °C was achieved, which resulted in microstructure refinement and significantly increased the hardness. Furthermore, plasticity anisotropy, a common problem in HCP structures, was suppressed by the ausforming treatment. This, in turn, reduced the scatter of the hardness.

Effect of Thermomechanical Treatments on the Mechanical Properties of New Low-Cost Ti-Fe-Nb-Zr Alloys

The development of new low-cost alloys composed of common elements that show high biocompatibility and mechanical properties matching with human bone is the target of many researches recently. Design and controlling the mechanical properties of newly developed set of Ti-xFe-3Zr-yNb (x=3-8 & y=2-3, at.%) low-cost alloys through applying different thermomechanical treatments is the aim of this work. Fe-content in the present designed alloys is changing in the range 3 to 8 at.%. The hardness and Young's modulus of the alloys were measured for the alloys in the solution treated, hot rolled and subsequent ageing at 400 °C and 550 °C. The phases separation and hence hardness of the aged alloys at 400 °C and 550 °C are highly dependent on the Fe-content in the alloy. The Young's modulus of the alloys is also changing with the Fe-content and heat treatment, where lowest modulus (~80GPa) is shown in the Ti-5Fe-3Zr-3Nb alloy in the solution treated condition.

Microstructures and Mechanical Properties of Precipitation-Hardenable Magnesium–Silver–Calcium Alloy Sheets

Precipitation hardening provides one of the most common strengthening mechanisms for magnesium (Mg) alloys. Here, we report a new precipitation-hardenable Mg sheet alloy based on the magnesium–silver–calcium system. In a solution treated condition (T4), the strength of Mg–xAg–0.1Ca alloys is enhanced with increasing the Ag content from 1.5 wt.% to 12 wt.%. The Mg–12Ag–0.1Ca (wt.%) alloy sheet shows moderate tensile yield strengths of 193 MPa, 130 MPa, 117 MPa along the rolling direction (RD), 45° and transverse direction (TD) in the T4-treated condition. Subsequent artificial aging at 170 °C for 336 h (T6) increases the tensile yield strengths to 236 MPa, 163 MPa and 143 MPa along the RD, 45° and TD, respectively. This improvement in the tensile yield strength by the T6 treatment can be ascribed to the formation of AgMg4 precipitates lying on the {112¯0}ɑ and pyramidal planes. Our finding is expected to stimulate the development of precipitation-hardenable Mg–Ag-based wrought alloys with high strength.

Influence of Precipitation on Twinning in a Mg-Al-Zn Alloy

A textured Mg-Al-Zn alloy rolled plate was solution treated and aged at 320 oC for 2 h and 116 h, respectively. Afterwards, the three conditions were compressed at room temperature along the transverse direction to activate {110} twinning. Ageing treatments were observed to strengthen the alloy in relation to the solution-treated condition. This has been mainly attributed to the restricted lateral growth of twins in the presence of particles and thus to the additional stress required for twin growth. Accordingly, a slightly reduced twin volume fraction, but an increased number of smaller twins was observed after compression in the aged samples.

The effects of solution treatment on the microstructure of the cast Ni-based IN100 superalloy

In this research, the effects of the partial, full and partial + full solution heat treatments followed by aging at 900 °C for 10 h, on the microstructure of cast Ni-based IN100 superalloy were assessed. It has been found that, the alloy in the partial + full solution treated condition had the optimal combination of γ’ morphology, volume fraction and size. In this condition, the alloy possesses a cubic primary γ’with an average size of 470±10nm and 45% volume fraction. Discrete M23C6 and M6C carbides were formed at the grain boundaries and the morphology of the cubic MC carbide was changed to the spherical shape. In addition, the volume fraction of γ’/γ eutectic phase dropped to half of its value, compared to the as-cast alloy. During partial solution treatment followed by aging, discrete carbides were formed at the grain boundaries. This treatment without full solutioning was not an effective method to provide an optimal volume fraction and arrangement of γ’ and MC carbides morphology. Full solutioning alone, changed the cubic morphology of the primary γ’ and the blocky MC carbides to the spherical shape.