CE alloys and properties

Osprey® CE alloys comprise a range of mainly binary hyper-eutectic silicon-aluminium alloys (note – not AlSiC composites) where increasing silicon content results in lower expansion coefficients and increasing specific stiffness.

Alloys range

The table shows our standard range of CE alloys. Mechanical and thermal properties for the alloys are found in separate tables below.

Alloys
Osprey® alloy CTE, ppm/°C Al/Si ratio, %
CE17F 17 73/27
CE17MF 17 73/27
CE15F* 15 65/35
CE13F 13 58/42
CE11F 11 50/50
CE9F 9 40/60
CE8F* 8 35/65
CE7F 7 30/70
CE6F 6 20/80
CE5F* 5 13/87

*Contact us for more data about this alloy

Mechanical properties

Mechanical properties (typical values)
CE17F CE17MF CE13F CE11F CE9F CE7F CE6F
Composition Al-27%Si Al-27%Si Al-42%Si Al-50%Si Si-40%Al Si-30%Al Si-20%Al
Tensile strength, ultimate ≥160  175-3123) 205 193  181 ≥100  N/A
Yield strength, MPa  100 282 147  189 - - N/A
Bend strength (three point), Mpa - - 300  300  300  270 3191)
Young's modulus, GPa  91.8  91.82)  101.9  121.4 118 129.2  130
Rigidity modulus, GPa  35.8  35.82)  42.22)  48.6 46  51.6 N/A
Poisson's ratio  0.28 0.282)  0.272)  0.29 0.29 0.26  N/A
Density, g/cc  2.6 2.6  2.55   2.51 2.47  2.43  2.352)
Hardness, Hv  60  75–1323) 90 - 230 - N/A

1) Test pieces 4 mm x 3 mm x 40 mm
2) Calculated values
3) Depending on heat-treatment condition

Thermal properties

Coefficient of thermal expansion, ppm/ºC (typical values)
CE17F CE17MF CE13F CE11F CE9F CE7F
Composition1) Al-27%Si Al-27%Si Al-42%Si Al-50%Si Si-40%Al Si-30%Al
100K–200K - - - 7.8 - -
200K–300K - - - 10.6 - -
100K–300K - - - 9.2 - -
-60–200ºC - - - 11.6 - 7.6
Room temp. 15.3 15.3 12.2 11.4 9.1 7.2
25–200ºC 17.1 17.1 13.7 12.3 10.2 8.3
25–300ºC 18.1 18.1 14.6  12.9 10.9  8.8 
25–400ºC  18.7 18.7 15.2 13.4 11.3 9.2
25–500ºC  19 19 15.5 13.7 11.4 9.7
Thermal conductivity, W/m.K (typical values)
CE17F CE17MF CE13F CE11F CE9F CE7F
Composition1) Al-27%Si Al-27%Si Al-42%Si Al-50%Si Si-40%Al Si-30%Al
At -100ºC - - - - - 180
At -50ºC - - - - 1292) 140
At -0ºC - - - - - 135
At 25ºC 177.4 146.8 145 132 121 120
At 50ºC - - - - - 110
At 100ºC - - - - 125* 110
At 200ºC 151.2 146.5 - - 108* 100
At 300ºC - - - - 98* 88
At 400ºC - - - - 90* 80
At 500ºC - - - - 85* 75
Specific heat, J/kgºC 846.3 767.25 857* 754* 780* 785*

* Calculated values

Microstructure

In the molten state Si and Al are mutually soluble, whereas in the rapidly solidified condition there is minimal solubility of Si in Al (< 0.3%) and even less solubility of Al in Si. The products are true alloys rather than metal-matrix composites (such as AlSiC) as all the phases present originate from an homogeneous melt.

The Al phase is continuous up to ~ 85%Al. Over approximately 40% Si, the Si phase also becomes continuous, offering a co-continuous duplex alloy (similar to AlBe alloys).

The continuous Si phase produces a stiff alloy with low thermal expansion and low internal stresses, whereas the continuous Al phase enhances thermal conductivity and toughness and lowers electrical resistance.

Consequently, as the Al content is increased, electrical conductivity, thermal conductivity, strength, toughness, CTE and machinability are also increased. For these reasons, it is best to choose the highest Al content alloy that is acceptable for the application.

Although Sandvik can supply machined components with Si contents as high as 85% Si (i.e. CE5F), the relative brittleness of this composition means whenever feasible it is often better to compromise on the exact expansion match required and use a lower Si content alloy. For example, Kovar®* packages (with a CTE of ~ 7ppm/°C) have been successfully replaced with CE9F, CE11F and even CE13F.

* Kovar is a trademark of Carpenter Technology Corporation

A range of CTE

CTE range graph 880x480.jpg

The coefficient of thermal expansion (CTE) for Osprey® CE alloys range from 5 to 17 ppm/K. The graph shows the CTE for two of our most common alloys.

Compare with other materials

Osprey® CE alloys are lighter and also offer other advantages compared to many competitive materials.

View comparison table


Working with CE alloys

Find information on, for example, machining, welding and plating.

Learn about processing of CE alloys


FAQ about CE alloys

Want to know more? View the most frequently asked questions about controlled expansion alloys (CE alloys).

Go to the FAQ page


Main characteristics of CE alloys

  • Controlled thermal expansivity:
    5–17 ppm/°C
  • Low density: < 2.5 gm/cc
  • High thermal conductivity:
    120–180 W/m K
  • High specific stiffness:
    39 to 54 x103 Nm/g
  • Machinable, plateable and weldable

Applications

Osprey® CE alloys are used in, for example, structural products, wafers and thermal management products.

Application examples

Our process

Based on our well-established process, we provide finished components according to custom design.

Learn about our process

Proven performance

Our alloys improve component performance all the way from earth to outer space.

View cases in brief