in this study, ultrafine grained 2024 al alloy based b4c particles reinforced composite was produced by mechanical milling and hot extrusion. mechanical milling was used to synthesize the nanostructured al2024 in attrition mill under argon atmosphere up to 50h. a similar process was used to produce al2024-5%wt. b4c composite powder. to produce trimodal composites, milled powders were combined w...

A dislocation bow-out model has been developed to explain the strength of ultra-fine grained (UFG) materials with grain size roughly between 20 nm to 500 nm. In the model, perfect dislocations are assumed to be nucleated at grain-boundary sources and bow out between two pinning points on a boundary. Yielding is considered to occur when a dislocation takes a semi-circular shape under applied str...

Accumulative Roll-Bonding (ARB) is one of the more recently developed techniques capable of producing bulk ultra-fine grained (ufg) metals. There are still many aspects of the behavior of ufg metals that lacks an in-depth understanding, such as a generalized view of the factors that govern the cyclic deformation mechanism(s). This study aims to advance the understanding of the cyclic deformatio...

Nuclear energy provides more than 10% of electrical power internationally, and the increasing engagement of nuclear energy is essential to meet the rapid worldwide increase in energy demand. A paramount challenge in the development of advanced nuclear reactors is the discovery of advanced structural materials that can endure extreme environments, such as severe neutron irradiation damage at hig...

This paper provides an overview on obtaining low-carbon ultra-fine grained dual-phase steels through rapid intercritical annealing of cold-rolled sheet as improved materials for automotive applications. A laboratory processing route was designed that involves cold-rolling of a tempered martensite structure followed by a second tempering step to produce a fine grained aggregate of ferrite and ca...

Ti Grade 2 was prepared by cryogenic attritor milling in liquid nitrogen and liquid argon. Two types of milling balls were used—stainless steel balls and heavy tungsten carbide balls. The effect of processing parameters on particle size and morphology, contamination of powder and its microhardness was investigated. Milling in liquid nitrogen was not feasible due to excessive contamination by ni...

1 List of symbols and abbreviations 3 Chapter 1: INTRODUCTION 6 Chapter 2: LITERATURE SURVEY 8 2.1: The essence of ultra fine grained materials 8 2.2: Severe plastic deformation: a method for producing UFG microstructure 11 2.3: Physical properties of materials derived from GB character 15 2.4: Non-equilibrium GBs: theoretical aspects 16 2.4.1: Conventional models for GB structure 16 2.4.2: Mod...

Equal channel multi angular pressing (ECMAP) process is the efficient method to enhance the productivity of ultra-fine grained (UFG) materials, by increasing process continuity and as a result decreasing process required time. Comparing repetitive ECAP method, in the same period, the number of passes can be done by ECMAP. In this article, ECMAP of AL strips in two typical annealed and as receiv...

aisi 304l austenitic stainless steel with different grain sizes of 0.5 -12 μm was obtained through the martensiticprocess. corrosion behavior of different samples was investigated in a 0.5m hcl solution using open circuitpotential, potentiodynamic polarization and electrochemical impedance spectroscopy tests. also, the correlationbetween the grain size and pitting corrosion resistance was asses...