1.1 Background

It’s well known, Aluminium atoms are arranged in a face-centered cubic (fcc) structure [1]. It is a good thermal and electrical conductor, having 59%   the conductivity of copper, both thermal and electrical, while having only 30% of copper's density. Aluminium is capable of superconductivity, with a superconducting critical temperature of 1.2 Kelvin and a critical magnetic field of about 100 Gauss [2]. It’ s also the most common material for the fabrication of superconducting qubits [3]. However, Aluminium is the third most abundant element into the Earth's crust. Aluminium makes up about 8% of the crust by the mass, though it is less common in the mantle below. This metal is so chemically reactive; the native specimens are rare and limited to extreme reducing environments. Instead, it is found combined in over 270 different minerals [4]. The chief ore of it is bauxite. Also it’s remarkable for the metal's low density and its ability to resist corrosion through the phenomenon of passivation. Alloys of Aluminium are vital to the aerospace industry and important in transportation structures, for instance window frames and building facades. Its sulfates and oxides are the most useful compounds. Although its spread in the environment, there is no known form of life uses Aluminium salts metabolically, but it is good tolerated by animals and plants [5]. Also, despite these salts' abundance, the potential for a biological role still investigated, and researches are continued. On the other hand, Aluminium alloys with a wide range of properties are used in engineering structures. However, Aluminum’s alloy types are now classified by a number system (ANSI) or names reflecting their principle constituents (DIN and ISO). The right selection alloy for a given application requires considerations of its tensile density, strength, formability, workability, ductility, weldability, and corrosion resistance, to name a few. So, Aluminium alloys are used extensively in aircraft due to their high strength-to-weight ratio. Also, it does not get a high tensile strength that is needed for helicopters and airplanes. Therefore, a tensile structure is a mix of elements carrying only tension and no bending or compression [6].

Furthermore, membrane structure of tensile is most commonly used as a roof, as they can economically and attractively span large distances. Otherwise, some materials break very sharply, without plastic deformation, in what is referred to as a brittle failure. Others, which are more ductile, including most metals, experience some plastic deformation and possibly necking before fracture. The ultimate tensile structure is usually found by performing a tensile test and recording the engineering stress versus strain. The highest point of the stress–strain curve (see point 1 on the engineering stress/strain diagrams below) is the UTS. It is an intensive property; therefore its value is not dependent on the size of the test specimen. However, it is a function of other factors, such as the preparation of the specimen, the presence or otherwise of surface defects, and the temperature of the test environment and material. So, Tensile strength is described as a stress, which is measured as force per unit area. For some non-homogeneous materials (or for assembled components) it can be reported just as a force or as a force per unit width. In the International System of Units (SI), the unit is the pascal (Pa) (or a multiple thereof, often megapascals (MPa), using the SI prefix mega); or, equivalently to pascals, newtons per square metre (N/m²). A United States customary unit is pounds per square inch (lb/in² or psi), or kilo-pounds per square inch (ksi, or sometimes kpsi), which is equal to 1000 psi; kilo-pounds per square inch are commonly used in one country (USA), when measuring tensile strengths [7]. Therefore, we plan to investigate the influence of a gradient structure on tensile properties of Aluminium which may open new views on the way of Aluminium industrial applications.