آنالیز SEM و اشعه ایکس - SEM and X-ray Microanalysis

SEM and X-ray Microanalysis Image Formation and Interpretation

آنالیز اشعه ایکس و SEM - تفسیر و تشکیل تصویر

ABSTRACT

Scanning electron microscopy is a technique in which images form the major avenue of information to the user. A great measure of the enormous popularity of the SEM arises from the ease with which useful images can be obtained. Modern instruments incorporate many computer-controlled, automatic features that permit even a new user to rapidly obtain images that contain fine detail and features that are readily visible, even at scanning rates up to that of television (TV) display. Although such automatic “computer-aided” microscopy provides a powerful tool capable of solving many problems, there will always remain a class of problems for which the general optimized solution may not be sufficient.

متالورژی منگنز -Manganese metallurgy

Manganese metallurgy review . Part I: Leaching of ores/secondary materials and

recovery of electrolytic/chemical manganese dioxide

مروری بر متالورژی منگنز. قسمت I: فروشویی سنگ‌های‌معدنی/مواد ثانویه

و بازیافت الکترولیتی/شیمیایی دی‌اکسید منگنز

ABSTRACT

The world rapidly growing demand for manganese hasmade it increasingly important to develop processes for economical recovery of manganese from low grade manganese ores and other secondary sources. Part I of this review outlines metallurgical processes for manganese production from various resources, particularly focusing on recent developments in direct hydrometallurgical leaching and recovery processes to identify potential sources of manganese and products which can be economically produced. 

High grade manganese ores (N40%) are typically processed into suitable metallic alloy forms by pyrometallurgical processes. Low grade manganese ores (b40%) are conventionally processed by pyrometallurgical reductive roasting or melting followed by hydrometallurgical processing for production of chemical manganese dioxide (CMD), electrolytic manganese (EM) or electrolytic manganese dioxide (EMD).

اثر نرخ سرد شدن روی ساختار میکروسکوپی آلیاژ هایپر یوتکتیک Al-Ni

The influence of cooling rate on the microstructure of an Al–Ni hypereutectic alloy

اثر نرخ سرد شدن روی ساختار میکروسکوپی آلیاژ هایپر یوتکتیک Al-Ni

ABSTRACT

An Al–4 at.% Ni alloy was prepared by a melt spinning technique and characterized by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy and high resolution transmission electron microscopy. The resulting ribbon microstructure consists of intermetallic Al9Ni2 globular-like structures embedded within an aluminum matrix. Characteristic globules are nanometric (∼100 nm) and are mainly located at the grain boundaries. The resulting effect on the mechanical properties is the enhancement of the alloy hardness from 58 to 371 HV.

 

اثر ایتربیم روی خواص مکانیکی و ریزساختار آلیاژ آلومینیوم-منیزیم

Effects of Yb on the mechanical properties and microstructures of an Al–Mg alloy

اثر ایتربیم روی خواص مکانیکی و ریزساختار آلیاژ آلومینیوم-منیزیم

ABSTRACT

This paper reported a first study of the effects of Yb on the microstructures and mechanical properties of an extruded Al–Mg alloy. It has been shown that the addition of 0.3 wt.% Yb decreases the mechanical properties of the alloy since Mg- and Yb-containing constituents decrease the concentration of Mg solute atoms in Al matrix, and thus the solution strengthening effect. However, the addition of 1 wt.% Yb substantially improves the mechanical behavior of the alloy because the concentration of Yb solute atoms in Al matrix is high enough to generate solution strengthening effect. The improvement in the mechanical properties is due to the large work-hardening and high dislocation density caused by the interaction between dislocations and Yb and Mg solute atoms. The Yb and Mg atoms inhibit the dynamic recovery and recrystallization of the alloy, thus provide a uniformly distributed dislocation structure with high density.

 

تبلور مجدد و مقاومت به خوردگی آلیاژهای آلومینیوم-روی-منیزیم-مس

Effect of of Yb, Cr and Zr additions on recrystallization and corrosion resistance of Al–Zn–Mg–Cu alloys

اثر افزودن ایتربیم، کروم و زیرکونیوم روی تبلورمجدد و مقاومت به خوردگی آلیاژهای آلومینیوم-روی-منیزیم-مس

ABSTRACT

The effect of complex additions of Yb, Cr and Zr on recrystallization and corrosion resistance of Al–Zn–Mg–Cu alloy has been investigated. By complex additions of Yb, Cr and Zr to Al–Zn–Mg–Cu alloy, 20–50nm dispersoids were formed in Al matrix and identified by X-ray diffraction analysis and energy dispersive X-ray spectroscopy as Zn, Mg, Cu, Zr-containing YbCr2A120 with cubic CeCr2Al20 crystal structure. The dispersoids remarkably inhibited the recrystallization of Al matrix, and a lot of low angle grain boundary of the Al–Zn–Mg–Cu alloy by complex additions of Zr, Cr and Yb investigated by electron back scattered diffraction was retained. Complex additions of Yb, Cr and Zr to Al–Zn–Mg–Cu alloy remarkably enhanced resistance to stress corrosion cracking (KISCC) from 9.8 to 17.0MPam1/2, exfoliation corrosion from EB+ to EA and intergranular corrosion with the improved strength, fracture toughness and ductility.

 

راهنمای عملیات حرارتی آلیاژهای غیرآهنی- آلومینیوم و آلیاژهای آن Heat Treaters Guide

Heat Treater's Guide Nonferrous Alloys Wrought Aluminum and Aluminum Alloys

راهنمای عملیات حرارتی آلیاژهای غیرآهنی- آلومینیوم و آلیاژهای آن

ABSTRACT

3003 Aluminum: Microstructures. (a) 3003-0 sheet, annealed. Longitudinal section shows recrystallized grains. Grain elongation indicates rolling direction, but not the crystallographic orientation within each grain. Polarized light. Barker's reagent. 100x. (b) 3003-0 sheet, annealed. Same as adjoining microstructure, but shown at a higher magnification. Dispersion of insoluble particles of (Fe,Mn)Als (large) and aluminum-manganese-silicon (both large and small) was not changed by annealing.

 

تنش‌های پسماند در جوش‌های لب به لب اتصالات لوله غیرمشابه

Effect of the welding heat input on residual stresses in butt-welds of dissimilar pipe joints

اثر ورودی حرارت جوشکاری بر تنش‌های پسماند در جوش‌های لب به لب اتصالات لوله غیرمشابه

ABSTRACT

This study used finite element techniques to analyse the thermo-mechanical behaviour and residual stresses in dissimilar butt-welded pipes. The residual stresses at the surface of some weld specimens were measured experimentally by using the hole-drilling method. The results of the finite element analysis were compared with experimentally measured data to evaluate the accuracy of the finite element modelling. Based on this study, a modelling procedure with reasonable accuracy was developed. The developed finite element modelling was used to study the effects of welding heat input on magnitude and distribution of welding residual stresses in butt-welded pipes made of ferritic and austenitic steels. The hoop and axial residual stresses in dissimilar pipe joints of 8 mm thick for V-groove shape were studied. It is shown that the welding heat input has a significant effect on magnitude and distribution of residual stresses in the stainless steel side of the studied joints.

 

تنش پسماند حرارتی در فرآیند جوشکاری لیزری هیبریدی-GMA welding process

Numerical and experimental study of thermally induced residual stress in the hybrid laser–GMA welding process

مطالعه عددی و تجربی تنش پسماند حرارتی در فرآیند جوشکاری لیزری هیبریدی-GMA

ABSTRACT

A model based on a double-ellipsoidal volume heat source to simulate the gas metal arc welding (GMAW) heat input and a cylindrical volume heat source to simulate the laser beam heat input was developed to predict the temperature field and thermally induced residual stress in the hybrid laser–gas metal arc (GMA) welding process. Numerical simulation shows that higher residual stress is distributed in the weld bead and surrounding heat-affected zone (HAZ). Effects of the welding speed on the isotherms and residual stress of the welded joint are also studied. It is found that an increase in welding speed can reduce the residual stress concentration in the as-weld specimen. A series of experiments has been performed to verify the developed thermo-mechanical finite element model (FEM), and a qualitative agreement of residual stress distribution and weld geometrical size is shown to exist.

 

خزش در فلزات آمورف (شیشه فلزات) Creep in amorphous metals

Creep in amorphous metals

خزش در فلزات آمورف (شیشه فلزات)

ABSTRACT

This paper reviews the work on creep behavior of amorphous metals. There have been, overthe past several years, a few reviews of the mechanical behavior of amorphous metals. Ofthese, the review of the creep properties of amorphous metals by Schuh et al. though oldestof the three, is particularly noteworthy and the reader is referred to this article publishedin 2007. The current review of creep of amorphous metals particularly focuses on thoseworks since that review and places the work prior to 2007 in a different context where newdevelopments warrant.

 

ساخت پودرهای فلزی توسط الکترولیز

Forming metal powders by electrolysis

ساخت پودرهای فلزی توسط الکترولیز

ABSTRACT

Fossil fuels will eventually be replaced by renewables. Currently, the most feasible and efficient way of utilising renewable energy is to convert it to electricity. In response to this change, fossil energy-based pyrometallurgical processes will inevitably shift to electricity driven processes. This chapter considers the feasibility of direct conversion of mineral to metal powder using a new electrochemical method, the FFC Cambridge process. The discussion will be on the background of electrometallurgy and powder metallurgy, the principles of the new process and its application for metal powder production, and the direct route from oxide precursors to alloyed powders.