Charpy, Augustin Georges Albert

(b. Oullins, Rhône, France, 1 September 1865; d. Paris, France, 25 November 1945),

metallurgy, chemistry.

After graduating from the École Polytechnique in 1887, Charpy, in the school’s chemistry laboratory, prepared a doctoral thesis on the variations in volume and density of solutions as a function of temperature and concentration. In 1892 he became an engineer at the Laboratoire d’Artillerie de la Marine and directed his research toward the study of metals and their alloys. He joined the Compagnie de Chatillon Commentry in 1898 and quickly became its technical director. In 1920 he was named director general of the Compagnie des Acieries de la Marine et Homécourt. He was elected to the Académie des Sciences in 1918, in the newly created section of industrial applications of science.

Along with Osmond and Henry Le Chatelier, Charpy was one of the three founders of the science of alloys in France. At the Laboratoire de la Marine he studied the quenching of steel and elucidated the influence of the quenching temperature by correlating the mechanical properties and the temperature values of the critical points. He recognized the lamellar form of eutectic alloys and deduced from it an explanation of the structure of these steels. He gave experimental results for several régions of the solubility diagram of carbon in iron.

Charpy was the first to introduce pyrometry into industrial practice in France, and he constructed the first electrical resistance furnace with platinum elements.

After studying the production of steels, Charpy turned his attention to measuring their brittleness; to this end he devised the pendulum drop hammer that bears his name.

In 1902 Charpy was asked to examine silicon steel sheets. He showed that the magnetic hysteresis of a steel decreases as the size of the crystalline particle increases. He also studied the alloys of iron with silicon, aluminum, and antimony, and proposed a composition of 2 or 3 percent silicon, which was universally adopted for the low-leakage magnetic circuits fundamental in the manufacture of modern electrical equipment.

Charpy’s brilliant industrial career did not prevent him from dedicating part of his time to teaching; he was a very highly regarded professor at the École Supérieure des Mines in Paris and at the École Poly-technique.

BIBLIOGRAPHY

I. Original Works. Among Charpy’s articles, all of them published in Comptes rendus hebdomadaires des séances de l’Académie des sciences, are the following: “Sur la détermination des équilibres chimiques dans les systémes dissous,” 114 (1892), 665; “Influence de la température de recuit sur les propriétés mécaniques et la structure du laiton,” 116 (1893), 1131; “Sur la transformation produite dans le fer par une déformation permanente à froid,” 117 (1893), 850; “Sur la transformation allotropique du fer sous l’influence de la chaleur,” 118 (1894), 418, 868, 1258; 119 (1894), 735; “Sur l’acier au bore,” 120 (1895), 130; “Sur la constitution des alliages ternaires,” 126 (1898), 1645; “Sur l’équilibre chimique des systèmes fer-carbone,” 134 (1902), 103, written with L. Grenet; “Sur la dilatation des aciers aux températures élevées,” ibid., 540, written with L. Grenet; “Dilatométrie des aciers,” ibid., 598, written with L. Grenet; “Sur la dilatation des aciers trempés,” 136 (1903), 92, written with L. Grenet; “Sur le diagramme d’équilibre des alliages fer-carbone,” 141 (1905), 948; “Sur la solubilité de graphite dans le fer,” 145 (1907), 1277; “Sur l’action de l’oxyde de carbone sur le chrome, le nickel, leurs alliages et leurs oxydes,” 148 (1909), 560; “Sur la cémentation du fer par le carbone solide,” 150 (1910), 389, written with S. Bonnerot; “Sur les gaz des aciers,” 152 (1911), 1247; “Sur un dilatomètre non différentiel,” 212 (1941), 112; and “Sur les traitements thermiques des aciers,” 213 (1941), 421.

His books include Leçons de chimie (Paris, 1892), written with H. Gautier; and Notions élémentaires de sidérurgie (Paris, 1946), written with P. Pingault.

II. Secondary Literature. Two notice are R. Barthélemy, “Notice sur la vie et l’oeuvre de Georges Charpy,” in Notices et discours. Académie des sciences (June, 1947); and M. Caullery, “Annonce du décès de M. G. Charpy,” in Comptes rendus hebdomadaires des séances de l’Académie des sciences, 221 (1945), 677.

Georges Chaudron