Grain refinement not only enhances the mechanical performance of as-cast metallic materials but also provides an effective mechanism for controlling cast defects, such as macro-segregation, porosity and coarse second phase particles. Therefore, understanding grain alloys with different solute additions is both theoretical practical importance. Although extensive research has been carried out ov...

This brief review describes the major features of grain boundary mobility in metals and current limitations in our theoretical understanding. Although thermally activated exchange of atoms across boundaries provides a basic picture of grain boundary correct to within an order of magnitude, no refinement of this theory is available that accounts for the experimental characteristics of grain mobi...

In this research, St37 and 316L steel sheets were welded using friction stir welding (FSW) process and effective parameters such as the rotational speed, linear speed of the tool, pin diameter, and their appropriate values were studied. The microstructure, hardness, and strength of the different welding regions were investigated. It was observed that in the stir zone (SZ), a mechanical operatio...

The application of magnesium alloys is greatly limited because of their relatively low strength and ductility. An effective way to improve the mechanical properties of magnesium alloy is to refine the grains. As the race for better materials performance is never ending, attempts to develop viable techniques for microstructure refinement continue. Further refining of grain size requires, however...

in this article, commercially pure copper samples were severely deformed by equal channel angular pressing (ecap) up to eight passes at room temperature. the effects of severe plastic deformation on the microstructure, mechanical properties, and electrical conductivity of the copper were investigated. the microstructure evolution was followed by optical microscope and field emission scanning el...

The structural and magnetic properties of the melt-spun Pr2Fe14B/a-Fe nanocomposite powders consolidated via shock-wave compression and subjected to postshock thermal treatment were investigated. Shock compression results in grain refinement, which leads to a reduction of an effective anisotropy and therefore an increase in the ferromagnetic exchange length, resulting in an enhanced exchange co...

Grain refinement via semi-solid deformation is desired to obtain superior mechanical properties of cast components. Using quantitative in situ synchrotron X-ray tomographic microscopy, we show an additional mechanism for the reduction of grain size, via liquation assisted transgranular cracking of semi-solid globular microstructures. Here we perform localized indentation of Al-15wt.%Cu globular...