IB Design Technology 4.2a Metals and Metallic Alloys Questionbank

(b) Evaluate the mechanical and thermal requirements that lead to the selection of nickel-based superalloys for the manufacture of jet engine turbine blades.

Which of the following best explains why an alloy, such as bronze or brass, is typically harder than a pure metal?

Which of the following is the primary alloying element in stainless steel that provides its corrosion resistance?

Metallic alloys are frequently engineered to exhibit specific mechanical properties that pure metals lack. The diagram below illustrates the differences in atomic arrangement between a pure metal and one of its alloys.

Which of the following correctly explains why the structural change shown in the alloy diagram makes the material harder than the pure metal?

Warping

Seasoning

Tempering

Felting

The alloying process removes delocalized electrons, which strengthens the electrostatic attraction between ions.

The introduction of different-sized atoms distorts the regular lattice, making it more difficult for layers of atoms to slide over each other.

Chemical reactions between the metals create a rigid network of covalent bonds that prevents deformation.

The different metals form a protective oxide layer inside the structure that acts as a physical barrier to movement.

Copper

Chromium

Nickel

Carbon

The presence of atoms of different sizes disrupts the regular arrangement, preventing the layers from sliding over each other easily.

The addition of different elements increases the concentration of delocalised electrons, which creates much stronger ionic attractions.

The alloying elements form covalent cross-links between the atoms of the host metal, locking them into a fixed 3D framework.

The larger atoms create gaps in the lattice that act as buffers, allowing the material to absorb more energy before it breaks.