25 1.1.5.10 Ductility. 23

26 1.1.5.11 Creep. 23

27 1.1.6 Impact Strength 24

28 1.1.7 Fracture Characteristics. 24

29 1.2 Literature Review 25

30 1.3 Problem Statement&Aims. 27

CHAPTER TWO

1 2 Methodology. 27

2 2.1 Metallography of Aluminium. 28

3 2.1.1 Preparation of Gradient Structure. 28

4 2.1.1.1 Grinding. 28

5 2.1.1.2 Polishing. 28

6 2.1.1.3 Etching. 29

7 2.1.1.4 Microstructures. 30

8 2.1.1.5 Microscopic Analyzes. 30

9 2.1.2 Hardness Testing. 31

10 2.1.3 Surface Roughness. 31

11 2.1.3.1 Preparation of Samples. 31

12 2.1.3.2 Measurements. 31

13 2.1.4 Electron Backscatter Diffraction of Aluminium (EBSD). 31

CHAPTER THREE

1 3 Results. 32

2 3.1 The Gradient Metallography Structure. 32

3 3.2 Metallic Hardness. 33

4 3.3 Metallic Roughness. 34

5 3.4 Electron Backscatter Diffraction of Aluminium (EBSD). 35

CHAPTER FOUR

1 4.1 Discussion. 36

2 4.2 Conclusion. 38

CHAPTER FIVE

1 5 References. 39

• List of Supplementary Figures

Title Page

Figure 1: Atomic structure of Aluminium 9

Figure 2: Volume per unit weight. 10

Figure 3: Pitting Corrosion Behaviour of 3103 Mill Finish Aluminium 14

Sheet

Figure 4: Thermal Expansion Matching Using MMCs 15

Figure 5: Sliding and Rigid Joints of Aluminium/ Steel 16

Structures

Figure 6: Brazing of Aluminium Using Clad Sheet 17

Figure 7: Plastic Yield Behaviour of Aluminium and Mild Steel. 19

Figure 8: Elongation of Aluminium at Ambient and Elevated 21

Temperature.• List of Figures

Title Page

Figure 9: Microstructure Metallography of Aluminium gradient 33 obtained by RASP and microscopic by magnifications 200x-500x, A. a

photo of the solid aluminum metallic was investigated; B&C two gradient layers of 600um thick represented metallography of prepared gradients the magnification is 200x. D. the metal microstructure in different performed parameters 40m/s, 40m/5min, and 16r/s under magnification 500X

Figure 10: An effect of gradients fractions on the strength tensile properties of Aluminium; A. three colors of different hardness evaluation red color reflects the high refinement of metal, green color no changes than normal but the blue color reflects the low refinement values; B. the micro-hardness value resulted by different distance on the metal surface; C&D. represented two effects (1) the micro-crack decreases strength. (2) Grain refinement increases strength.

Figure 11: Aluminum surface parameter confirmed significant effects 34 of a gradient structure on the tensile properties of aluminum; A. Surface Profile [Ra=0.64 μm, εFp=2.12 μm]; B. view of metallic surface roughness under confocal microscope; C. Influence exerted by

the average dimension of the abrasive particle on the sizes of the considered surface roughness parameters; D. different surface roughness parameters upon the time.

Figure 12: EBSD patterns from: a) the tested Aluminium with 36 face-center-cubic (FCC) structure; b) grain boundaries included for analyses with scanned area.

Abbreviation list

FCC Face-centered cubic

CG Coarse Grained

EBSD Electron Backscatter Diffraction

GND Gradient Nano Dislocation

GS Gradient Structure

IACS International Annealed Copper Standard

NS Nano Structured

SMGT Surface Mechanical Grinding Treatment

SMAT Surface Mechanical Attrition Treatment

CHAPTER ONE

1. Introduction Preface

Virtually, the structure and properties of a material surface control their applications in engineering fields. So, the optimization of the surface microstructure and properties of any materials could be an effective approach to improve the global behavior and service lifetime of those materials. However, optimizing surface properties by refining grains in surface layers to the nanometer scale (referred to as surface Nano-crystallization) provides the more promising practical industrial applicability. Consequently, Aluminium is a relatively soft, durable, lightweight, ductile, and malleable metal with appearance ranging from silvery to dull gray, being dependent on the surface roughness. It is nonmagnetic and does not easily ignite. A fresh film of Aluminium serves as a good reflector (approximately 92%) of visible light and an excellent reflector (as much as 98%) of medium and far infrared radiation. Yield strength of pure Aluminium is 7–11 MPa, while Aluminium alloys have yield strengths ranging from 200 MPa to 600 MPa. Aluminium contains about one-third density and stiffness of steel. It is also easily machined, cast, drawn and extruded.