Article 5: Engines
5.12	Materials and Construction - Definitions
5.12.1	X Based Alloy (e.g. Ni based alloy) – X must be the most abundant element in the alloy on a %w/w basis. The minimum possible weight percent of the element X must always be greater than the maximum possible of each of the other individual elements present in the alloy.
5.12.2	X-Y Based Alloy (e.g. Al-Cu based alloy) – X must be the most abundant element as in 5.12.1 above. In addition element Y must be the second highest constituent (%w/w), after X in the alloy. The mean content of Y and all other alloying elements must be used to determine the second highest alloying element (Y).
5.12.3	Intermetallic Materials (e.g. TiAl, NiAl, FeAl, Cu3Au, NiCo) – These are materials where the material is based upon intermetallic phases, i.e. the matrix of the material consists of greater then 50%v/v intermetallic phase(s). An intermetallic phase is a solid solution between two or more metals exhibiting either partly ionic or covalent, or metallic bonding with a long range order, in a narrow range of composition around the stoichiometric proportion.
5.12.4	Composite Materials – These are materials where a matrix material is reinforced by either a continuous or discontinuous phase. The matrix can be metallic, ceramic, polymeric or glass based. The reinforcement can be present as long fibres (continuous reinforcement); or short fibres, whiskers and particles (discontinuous reinforcement).
5.12.5	Metal Matrix Composites (MMC’s) – These are materials with a metallic matrix containing a phase of greater than 2%v/v which is not soluble in the liquid phase of the metallic matrix.
5.12.6	Ceramic Materials (e.g. Al2O3, SiC, B4C, Ti5Si3, SiO2, Si3N4) – These are inorganic, non metallic solids.
5.13	Materials and construction – General
5.13.1	Unless explicitly permitted for a specific engine component, the following materials may not be used anywhere on the engine : Magnesium based alloys Metal Matrix Composites (MMC’s) Intermetallic materials Alloys containing more than 5% by weight of Beryllium, Iridium or Rhenium.
5.13.2	Coatings are free provided the total coating thickness does not exceed 25% of the section thickness of the underlying base material in all axes. In all cases the relevant coating must not exceed 0.8mm.
5.14	Materials and construction – Components
5.14.1	Pistons must be manufactured from an aluminium alloy which is either Al-Si ; Al-Cu ; Al-Mg or Al-Zn based.
5.14.2	Piston pins must be manufactured from an iron based alloy and must be machined from a single piece of material.
5.14.3	Connecting rods must be manufactured from iron or titanium based alloys and must be machined from a single piece of material with no welded or joined assemblies (other than a bolted big end cap or an interfered small end bush).
5.14.4	Crankshafts must be manufactured from an iron based alloy. No welding is permitted between the front and rear main bearing journals. No material with a density exceeding 19,000kg/m3 may be assembled to the crankshaft.
5.14.5	Camshafts must be manufactured from an iron based alloy. Each camshaft and lobes must be machined from a single piece of material. No welding is allowed between the front and rear bearing journals.
5.14.6	Valves must be manufactured from alloys based on Iron, Nickel, Cobalt or Titanium. Hollow structures cooled by sodium, lithium or similar are permitted.
5.14.7	Reciprocating and rotating components : Reciprocating and rotating components must not be manufactured from graphitic matrix, metal matrix composites or ceramic materials. This restriction does not apply to the clutch and any seals ; Rolling elements of rolling element bearings must be manufactured from an iron based alloy ; Timing gears between the crankshaft and camshafts (including hubs) must be manufactured from an iron based alloy.
5.14.8	Static components : Engine crankcases and cylinder heads must be manufactured from cast or wrought aluminium alloys. No composite materials or metal matrix composites are permitted either for the whole component or locally. Any metallic structure whose primary or secondary function is to retain lubricant or coolant within the engine must be manufactured from an iron based alloy or an aluminium alloy of the Al-Si, Al-Cu, Al-Zn or Al-Mg alloying systems. All threaded fasteners must be manufactured from an alloy based on Cobalt, Iron or Nickel. Composite materials are not permitted. Valve seat inserts, valve guides and any other bearing component may be manufactured from metallic infiltrated pre-forms with other phases which are not used for reinforcement.