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Hexaferrum and epsilon iron (ε-Fe) are synonyms for the hexagonal close-packed (HCP) phase of iron that is stable only at extremely high pressure. A 1964 study at the University of Rochester mixed 99.8% pure α-iron powder with sodium chloride , and pressed a 0.5-mm diameter pellet between the flat faces of two diamond anvils.
The first 3 digits often match older 3-digit numbering systems, while the last 2 digits indicate more modern variations. For example, Stainless Steel Type 310 in the original 3-digit system became S31000 in the UNS System. The more modern low-carbon variation, Type 310S, became S31008 in the UNS System.
File:Diagramma_di_fase_del_ferro_puro.svg licensed with Cc-by-sa-3.0, GFDL 2010-09-11T13:37:42Z Daniele Pugliesi 470x450 (23026 Bytes) piccole correzioni sui valori 2010-09-11T11:59:22Z Daniele Pugliesi 470x450 (23026 Bytes) Correggo errore: si parla di ferrite solo se è presente carbonio, questo diagramma si riferisce invece al ferro puro.
The diagram depicts two astrophysical quantities of stars, their iron abundance relative to hydrogen [Fe/H] - a tracer of stellar metallicity - and the enrichment of alpha process elements relative to iron, [α/Fe]. The iron abundance is noted as the logarithm of the ratio of a star's iron abundance compared to that of the Sun:
Iron-carbon phase diagram. α-Iron is a fairly soft metal that can dissolve only a small concentration of carbon (no more than 0.021% by mass at 910 °C). [133] Austenite (γ-iron) is similarly soft and metallic but can dissolve considerably more carbon (as much as 2.04% by mass at 1146 °C).
Natural iron (26 Fe) consists of four stable isotopes: 5.845% 54 Fe (possibly radioactive with half-life > 4.4 × 10 20 years), [4] 91.754% 56 Fe, 2.119% 57 Fe and 0.286% 58 Fe. There are 28 known radioisotopes and 8 nuclear isomers, the most stable of which are 60 Fe (half-life 2.6 million years) and 55 Fe (half-life 2.7 years).
The A 2 line forms the boundary between the beta iron and alpha fields in the phase diagram in Figure 1. Similarly, the A 2 boundary is of only minor importance compared to the A 1 , A 3 and A cm critical temperatures. The A cm, where austenite is in equilibrium with cementite + γ-Fe, is beyond the right edge in Fig. 1.
The Mersenne Twister is a general-purpose pseudorandom number generator (PRNG) developed in 1997 by Makoto Matsumoto (松本 眞) and Takuji Nishimura (西村 拓士). [1] [2] Its name derives from the choice of a Mersenne prime as its period length. The Mersenne Twister was designed specifically to rectify most of the flaws found in older PRNGs.