Effect of aging temperature on the microstructures and mechanical properties of ZG12Cr9Mo1Co1NiVNbNB ferritic heat-resistant steel

The effect of aging on the mechanical properties and microstructures of a new ZG12Cr9 MolColNiVNbNB ferritic heat resistant steel was investigated in this work to satisfy the high steam parameters of the ultra-supercritical power plant.The results show that the main precipitates during aging are Fe（Cr,Mo）23C6,V（Nb）C,and（Fe2Mo） Laves in the steel.The amounts of the precipitated phases increase during aging,and correspondingly,the morphologies of phases are similar to be round.Fe（Cr,Mo）23C6 appears along boundaries and grows with increasing temperature.In addition,it is revealed that the martensitic laths are coarsened and eventually happen to be polygonization.The hardness and strength decrease gradually,whereas the plasticity of the steel increases.What＇s more,the hardness of this steel after creep is similar to that of other 9%-12%Cr ferritic steels.Thus,ZG12Cr9 MolColNiVNbNB can be used in the project.

Formation Mechanism and Existing Form of Sb in Heat Resistance Mg-Gd-Y-Sb Alloy

The existing form and reaction mechanism of Sb in heat resistane Mg-Gd-Y-Sb rare earth magnesium alloy were investigated by inductive coupled plasma emission spectroscopy(ICP),scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),and X-ray diffraction(XRD).It is found that Sb tends to form high melting point intermetallics with rare earth elements of Gd and Y.The existing form of Sb is determined to be GdSb and SbY,respectively,which has high melting point(GdSb:2142℃/SbY:1782℃).Meanwhile,the first principle calculation and electronegativity difference calculation were performed to further understand the reaction mechanism.Therefore,the forming heat and binding energy were calculated.The experimental results show that the binding tendency of Sb element to Gd and Y is much stronger than that of it with other elements in this alloy,which results in the formation of high melting point of Gd-Sb and Y-Sb intermetallics,and finally leads to the high temperature resistant further improvement of the Mg-Gd-Y magnesium alloy.

Effects of Cr Content on the Microstructure and Properties of 26Cr–3.5Mo–2Ni and 29Cr–3.5Mo–2Ni Super Ferritic Stainless Steels

By using scanning electron microscopy, energy-dispersive spectrometry, X-ray diffraction, strength and hardness measurements, the microstructure, precipitation, mechanical properties, and corrosion resis- tance have been investigated for two super ferritic stainless steels, 26Cr-3.SMo-2Ni and 29Cr-3.5Mo- 2Ni, with the aim to consider the effect of Cr content. The results showed that with the addition of Cr content, the recrystallization temperature was increased; the precipitation of Laves and Sigma （o） phases was promoted and the mechanical properties of super ferritic stainless steel were modified. Further- more, the pitting corrosion resistance and corrosion resistance to H2SO4 of the two super ferritic stainless steels were improved. In addition, suitable annealing processing is a key factor to maintain integrated performance by optimizing microstructure and removing detrimental precipitation phases.

Synthesis of a novel naphthyl-based self-catalyzed phthalonitrile polymer

A novel naphthyl-based self-catalyzed phthalonitrile monomer was prepared via nucleophilic displacement reaction. The structure was characterized by Fourier infrared spectrum （FT-IR） and nuclear magnetic resonance （^1H NMR）. The polymerization mechanism was explored. Thermal properties were characterized by differential scanning calorimetry （DSC） and thermogravimetric analysis （TGA）, which demonstrated self-promoted behavior and excellent heat resistance.