Corus accepts Tata sale

Corus Auction

The deal between Tata and Corus has finally been agreed. A price was decided today in an auction between Corus and CSN.

Tata group have bought Corus for 6.2 bn pounds (source).

Shortly after Chairman of Tata Group, Ratan Tata, took a flight in an F16. This is part of deal for India to buy F16’s, also some part manufacture may be outsourced to TATA.

Ratan TATA F16

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45 nm transistors

BBC have written about Intel’s production of new microchip technology developed to replace the use of silicon chips – Chips push through nano-barrier. The change in materials also allows the reduction in size from 65 nm to 45 nm, whilst allowing thicker layers of material to be used which will reduce leakage of electrons from the transistors. This is a problem in strained silicon transistors which can only be a few atoms in thickness. These materials aren’t high-k metals as BBC reports, but are gates made from a high-k material and a metal (high-k/metal).

The materials used are high-k materials – where k (kappa) is the dielectric constant,

Material Dielectric constant source
Air 1 (definition)
Carbon Black 2.5 – 3.0
Cocaine (68° F) 3.1
Copper Oxide 18.1
Formamide (68° F) 84.0
Glass 3.7-10
Hydrogen Cyanide (70° F) 95.4
Iodine (107° F) 118.0
Iodine 11
Iodine (250° F) 118.0
Silicon 11.0 – 12.0
Silicon Dioxide 4.5
Syrup 50-80
Titanium Dioxide 110.00
Titanium Oxide 40-50
Water 4-88

Reduced leakage means more power efficient processors, which also means less heating, which means more transistors per chip, and more computation power. I don’t know if this technology can also be faster but I guess this is why the small size is desirable.

From Intel’s glossary relating to this technology found on Intels pages.

high-k material – A material that can replace silicon dioxide as a gate dielectric. It has
good insulating properties and also creates high capacitance (hence the term “high-k”)
between the gate and the channel. Both of these are desirable properties for high
performance transistors. “k” (actually the Greek letter kappa) is an engineering term for
the ability of a material to hold electric charge. Think of a sponge. It can hold a lot of
water. Wood can hold some but not as much. Glass can’t hold any at all. Similarly, some
materials can store charge better than others, hence have a higher “k” value. Also,
because high-k materials can be thicker than silicon dioxide, while retaining the same
desirable properties, they greatly reduce leakage.
leakage – Current flowing through the gate dielectric. In an ideal situation, the gate
dielectric acts as a perfect insulator. But as it is made ever thinner (in Intel’s 90nm
process, it is a mere 5 atomic layers thick!), current leaks through it. This results in
undesirable results. The transistor doesn’t behave as it should, and it consumes more
power than it should. Think of a leaky faucet that drips water, hence being very wasteful

Intel describe hafnium dioxide (HfO2), zirconium dioxide (ZrO2) and titanium dioxide (TiO2) to be high k materials. All have a dielectric constant or above 3.9, the “k” of silicon dioxide.

Does anyone know what this nano-barrier is that Intel broke as reported by BBC?

Empirical Rant

In metallurgy we often term very simple models to be `empirical models’ in contrast to `physical models’. I really wish there was a better name for the `empirical models` – since physical models are more empirical, and `empirical models’ are actually less empirical. Use of such equations can be very useful because they do provide a summary of observations with-in some range of observed behaviour. Even when a physical model exists these simple models are often still preferred because of the ease with which they can be used.

The source of my confusion is the now contradictory uses of the word empirical…

Physical models incorporate more physical understanding, are based on a theoretical understanding. Any theory can only be based on, and validated against, observations. (Edit: i.e. empirical observations)

A better description for our `empirical models’ would be Ad-hoc, make-do, summary or arbitrary.

Comparison of empirical and physical models
This is best described by an example. The martensite start temperature (MS) is often described by an equation of the form; MS = A*XC + B*XMn + C*XCr…

MS(C) = 521 – 353.C – 225.Si – 24.3.Mn – 27.4.Ni 0 17.7.Cr – 25.8.Mo

Another example is the use of various ‘carbon equivilant’s.
Carbon Equivilant = CE = C + Mn/5 + Mo / 5 + Cr/10 + Ni/50

Thomas Sourmail and Carlos Garcia-Mateo have written a paper on prediciton of M_S by various methods,
(Critical assessment of models for predicting the Ms temperature of steels, T. Sourmail and C. Garcia-Mateo Comp. Mater. Sci., 2005:34, p323-334) it is available on Thomas’s webpage;Predicting the martensite start temperature (Ms) of steels.

Ms/ K, all compositions in wt%
[8] 772-316.7C-33.3Mn-11.1Si-27.8Cr-16.7Ni-11.1Mo-11.1W
[9] 811-361C-38.9Mn-38.9Cr-19.4Ni-27.8Mo
[10] 772-300C-33.3Mn-11.1Si-22.2Cr-16.7Ni-11.1Mo
[11] 834.2-473.9C-33Mn-16.7Cr-16.7Ni-21.2Mo
[12] 812-423C-30.4Mn-12.1Cr-17.7Ni-7.5Mo
[12] 785-453C-16.9Ni-15Cr-9.5Mo+217(C)2-71.5(C)(Mn)-67.6(C)(Cr)

Potency of Elements on MS temperature (Change per weight percent).

N C Ni Co Cu Mn W Si Mo Cr V Al
-450 -450 -20 +10 -35 -30 -36 -50 -45 -20 -46 -53 P-1976
  • P-1976 F.B. pickering, `Physical metallurgy of stainless steel developments’, Int. Met. Rev., 21, pp 227-268, 1976.
  • 8 P. Payson and C. H. Savage. Trans. ASM, 33:261-281, 1944.
  • 9 R. A. Grange and H. M. Stewart. Trans. AIME, 167:467-494, 1945.
  • 10 A. E. Nehrenberg. Trans. AIME, 167:494-501, 1945.
  • 11 W. Steven and A. G. Haynes. JISI, 183:349-359, 1956.
  • 12 K. W. Andrews. JISI, 203:721-727, 1965.
  • 13 C. Y. Kung and J. J. Rayment. Metall. Trans. A, 13:328-331, 1982.

Neural network models have been developed to predict both martensite start and bainite start temperatures. It is also possible to calculate these using ‘physically’ based models based on thermodynamics.

They’re all just maths! 🙂