جستجوی مقالات مرتبط با کلیدواژه "composition" در نشریات گروه "مواد و متالورژی"

In this research the role of alloying elements on the microstructure and mechanical properties of an as cast and hot rolled high strength low alloy (HSLA) steel was studied. Different compositions with different amount of copper in the presence of nickel, hot rolled and quenched in oil. Tensile test, hardness test, scanning electron microscope (SEM) and optical microscope (OM) were used to evaluate different properties of each sample. The results showed that, all the samples revealed a ferrite-perlite structure in as cast structure, however finer structure with higher hardness was seen in the samples with higher amount of copper. Furthermore, in hot rolled samples, it was seen that addition of nickel and copper resulted in grain refinement. A remarkable drop was seen in elongation due to copper precipitation. Fractography also revealed that, increasing copper amount led to variation of fracture mechanism from ductile to shear ductile fracture.

Zirconium Diboride (ZrB2) powder was synthesized at low temperature via a Direct Molten Salt Reaction (DMSR) method. The influence of different salt compositions including eutectic mixture of (KF-NaF), (KF-KCl) and (KCl-NaCl) on the morphology and purity of the reaction products was studied. The obtained samples were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Furthermore, the formation mechanism of ZrB2 was investigated by DTA/TG. The results show that alongside eutectic mixture of chloride salt, ZrB2 powder can be obtained with eutectic mixture of fluoride salt. In addition, obtained ZrB2 powder without additional salt has hexagonal prism morphology, whereas ZrB2 particles prepared with eutectic mixture of fluoride salt have higher purity and particle size and hexagonal morphology as well. Synthesized ZrB2 Powder in chlorofluoride salt has lower particle size and purity and non-uniform morphology. Synthesized ZrB2 powder is different from starting material in term of morphology and particle size therefore the dissolution–precipitation mechanism may play a dominant role on the synthesis of ZrB2 during DMSR process.