Y alloy is a

nickel Nickel is a chemical element with symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive but large pieces are slow to ...

-containing

aluminium alloy An aluminium alloy (or aluminum alloy; see spelling differences) is an alloy in which aluminium (Al) is the predominant metal. The typical alloying elements are copper, magnesium, manganese, silicon, tin, nickel and zinc. There are two principal ...

. It was developed by the British National Physical Laboratory during

World War I World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, the United States, and the Ottoman Empire, with fightin ...

, in an attempt to find an aluminium alloy that would retain its strength at high temperatures.

Duralumin Duralumin (also called duraluminum, duraluminium, duralum, dural(l)ium, or dural) is a trade name for one of the earliest types of age-hardenable aluminium alloys. The term is a combination of '' Dürener'' and ''aluminium''. Its use as a tra ...

, an aluminium alloy containing 4%

copper Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkis ...

was already known at this time. Its strength, and its previously unknown

age hardening Precipitation hardening, also called age hardening or particle hardening, is a heat treatment technique used to increase the yield strength of malleable materials, including most structural alloys of aluminium, magnesium, nickel, titanium, and so ...

behaviour had made it a popular choice for

zeppelin A Zeppelin is a type of rigid airship named after the German inventor Count Ferdinand von Zeppelin () who pioneered rigid airship development at the beginning of the 20th century. Zeppelin's notions were first formulated in 1874Eckener 1938, pp ...

s. Aircraft of the period were largely constructed of wood, but there was a need for an aluminium alloy suitable for making engines, particularly

piston A piston is a component of reciprocating engines, reciprocating pumps, gas compressors, hydraulic cylinders and pneumatic cylinders, among other similar mechanisms. It is the moving component that is contained by a cylinder and is made gas-tig ...

s, that would have the strength of duralumin but could retain this when in service at high temperatures for long periods. The National Physical Laboratory began a series of experiments to study new aluminium alloys. Experimental series "Y" was successful, and gave its name to the new alloy. Like duralumin, this was a 4% copper alloy, but with the addition of 2% nickel and 1.5%

magnesium Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic ta ...

. This addition of nickel was an innovation for aluminium alloys. These alloys are one of the three main groups of high-strength aluminium alloys, the nickel–aluminium alloys having the advantage of retaining strength at high temperatures. The alloy was first used in the

cast Cast may refer to: Music * Cast (band), an English alternative rock band * Cast (Mexican band), a progressive Mexican rock band * The Cast, a Scottish musical duo: Mairi Campbell and Dave Francis * ''Cast'', a 2012 album by Trespassers William * ...

form, but was soon used for

forging Forging is a manufacturing process involving the shaping of metal using localized compressive forces. The blows are delivered with a hammer (often a power hammer) or a die. Forging is often classified according to the temperature at which i ...

as well. One of the most pressing needs was to develop reliable pistons for aircraft engines. The first experts at forging this alloy were '' Peter Hooker Limited'' of

Walthamstow Walthamstow ( or ) is a large town in East London, east London, England, within the Ceremonial counties of England, ceremonial county of Greater London and the Historic counties of England, ancient county of Essex. Situated northeast of Chari ...

, who were better known as The British Gnôme and Le Rhône Engine Co. They license-built the

Gnome A gnome is a mythological creature and diminutive spirit in Renaissance magic and alchemy, first introduced by Paracelsus in the 16th century and later adopted by more recent authors including those of modern fantasy literature. Its characte ...

engine and fitted it with pistons of Y alloy, rather than their previous

cast iron Cast iron is a class of iron–carbon alloys with a carbon content more than 2%. Its usefulness derives from its relatively low melting temperature. The alloy constituents affect its color when fractured: white cast iron has carbide impuriti ...

. These pistons were highly successful, although impressions of the alloy as a panacea suitable for all applications were less successful; a Gnôme cylinder in Y alloy failed on its first revolution. Banks, I Kept No Diary, p. 69

Frank Halford Major Frank Bernard Halford CBE FRAeS (7 March 1894 – 16 April 1955) was an English aircraft engine designer. He is best known for the series of de Havilland Gipsy engines, widely used by light aircraft in the 1920s and 30s. Career Educat ...

used

connecting rod A connecting rod, also called a 'con rod', is the part of a piston engine which connects the piston to the crankshaft. Together with the crank, the connecting rod converts the reciprocating motion of the piston into the rotation of the cranksh ...

s of this alloy for his

de Havilland Gipsy The de Havilland Gipsy is a British air-cooled four-cylinder in-line aircraft engine designed by Frank Halford in 1927 to replace the ADC Cirrus in the de Havilland DH.60 Moth light biplane. Initially developed as an upright 5 litre (300 ...

engine, but these other uses failed to impress Rod Banks.

Air Ministry The Air Ministry was a department of the Government of the United Kingdom with the responsibility of managing the affairs of the Royal Air Force, that existed from 1918 to 1964. It was under the political authority of the Secretary of State ...

Specification D.T.D 58A of April 1927 specified the composition and heat treatment of wrought Y alloy. The alloy became extremely important for pistons, and for engine components in general, but was little used for structural members of

airframe The mechanical structure of an aircraft is known as the airframe. This structure is typically considered to include the fuselage, undercarriage, empennage and wings, and excludes the propulsion system. Airframe design is a field of aerospa ...

s. In the late 1920s, further research on nickel-aluminium alloys gave rise to the successful

Hiduminium The Hiduminium alloys or R.R. alloys are a series of high-strength, high-temperature aluminium alloys, developed for aircraft use by Rolls-Royce ("RR") before World War II. They were manufactured and later developed by High Duty Alloys Ltd. T ...

or "R.R. alloys", developed by

Rolls-Royce Rolls-Royce (always hyphenated) may refer to: * Rolls-Royce Limited, a British manufacturer of cars and later aero engines, founded in 1906, now defunct Automobiles * Rolls-Royce Motor Cars, the current car manufacturing company incorporated in ...

Alloy composition

Heat treatment

As for many of the aluminium alloys, Y alloy age hardens spontaneously at normal temperatures after solution heat treating. The heat treatment is to heat it to for 6 hours, then to allow it to age naturally for 7–10 days. The

precipitation hardening Precipitation hardening, also called age hardening or particle hardening, is a heat treatment technique used to increase the yield strength of malleable materials, including most structural alloys of aluminium, magnesium, nickel, titanium, and so ...

that takes place during this ageing forms precipitates of both CuAl₂ and NiAl₃. The times required depend on the grain structure of the alloy. Forged parts have the coarsest eutectic masses and so take the longest times. When cast, chill casting is favoured over

sand casting Sand casting, also known as sand molded casting, is a metal casting process characterized by using sand as the mold material. The term "sand casting" can also refer to an object produced via the sand casting process. Sand castings are produced i ...

as this gives a finer structure that is more amenable to heat treatment.

Alloy composition

Heat treatment

References

See also