Chevenard, Pierre Antoine Jean Sylvestre

(b. Thizy, Rhône, France, 31 December 1888; d. Fontenay-aux-Roses, France, 15 August 1960),

metallurgy.

Chevenard studied at the École des Mines at Saint-Étienne, from which he graduated in 1910. He then joined the Société de Commentry Fourchambault et Decazeville, where he remained throughout his career, becoming its scientific director in 1935. In 1946 he was elected to the Academie des Sciences, in the section of industrial applications of science.

From his first assignment for the Societe de Commentry Fourchambault, at its works at Imphy, Chevenard pursued the investigations begun by Charles Edouard Guillaume, discoverer of the alloys Invar and Elinvar. He explored the physical properties of nickel and was subsequently able to provide the clockmaking industry with a remarkable series of alloys.

In 1917 Chevenard brought out several alloys that showed good resistance to creep at high temperatures and especially high resistance to corrosion. In particular the alloy A. T. G., with 60 percent nickel, 10 percent chromium, and 4 percent tungsten, was of great value in the chemistry of high pressures and temperatures-for example, in the synthesis of ammonia under very high pressure, developed by Georges Claude. Other applications of these alloys have included the fabrication of valves for internal combustion engines and blades for steam engines.

The first ferronickel alloys, however, were found to be susceptible to cracking. Chevenard showed that the heterogeneity of the solid solution was the main problem. He also perfected equipment to measure the degree of heterogeneity in iron-nickel-chromiumcarbon alloys and determined its quantitative influence on cracking.

Chevenard was also responsible for steam-resistant alloys (A. T. V.), solid solutions rich in chromium and very low in carbon. Certain additions render such alloys capable of sustaining structural hardening without damage to their resistance to chemicals.

The studies he carried out in this area enabled Chevenard to suggest new research. Ir is to this group of studies, in which the techniques of measurement played a primary role, that the name “precision metallurgy” has been given. In order to gain the precision necessary for such research on new alloys and for their preparation, Chevenard created a series of selfrecording devices, almost all of which were based on the optical tripod.

Chevenard’s micromachines, constructed for test samples 1,000 times smaller than the classic ones, permitted the examination of heterogeneous pieces with an exactness never attained before. Chevenard’s instruments facilitated the use of certain physical methods to such a degree that his name has passed from the device to the method itself: this is the case with the dilatometric and thermoponderal methods, through his differential dilatometer and his thermobalance.

In his dilatometric investigations Baros, which possesses a regular and reversible dilatation, was replaced by another standard alloy, Pyros, which is more rigid when heated and has an even more regular dilatation.

From 1923 to 1929 Chevenard, in collaboration with Albert Portevin, often transposed certain of his techniques and results to the study of alloys other than those of steel and nickel. It was then that he investigated by dilatometry the structural hardening of light alloys of aluminum.

BIBLIOGRAPHY

Among Chevenard’s papers, the following were published in the Comptes rendus hebdomadaires des séances de l’Academie des sciences: “Dilatation des aciers au nickel dans un grand intervalled de température,” 158 (1914), 175; “Dilatometre differentiel enregistreur,” 164 (1917), 916; “Changement thermique des proprietes elastiques desaciers au nickel,” 170 (1920), 1499 ; “Influence de l’ecrouissage et de la trempe sur les propriétés élastiques de divers metaux et alliages,” 181 (1925), 716, written with A. Portevin; “Anomalie du frottement interne des ferronickels réversibles,” 184 (1927), 378; “Causes de la variation de volume accompagnant le durcissement des alliages legers aluminium-cuivre,” 186 (1928), 144, written with A. Portevin; “Influence du revenu sur la dilatation et la duretedes alliages aluminium silicium trempes,” 191 (1930), 252, written with A. Portevin; “Micromachine a enregistrement photographique pour l’essai mecanique des metaux,” 200 (1935), 212; “Tres petite machine de traction a enregistrement photographique et son application a l’etude des fibres textiles,” 203 (1936), 841; “Corrosion intercristalline des ferronickels chromes carbures, ecrouis apres hypertrempe,” 204 (1937), 1167, written with X. Waché; “Nouveaux alliages du type élinvar susceptibles de durcissement structural,” ibid., 1231, written with L. Huguenin, X. Waché, and A. Villachon; “Amplificateur mécanique a grandissement supérieur á 1000. Application a l’enregistrement de la déformation visqueuse des metaux aux temperatures elevess,” 205 (1937), 107, written with E. Joumier; “Thermoelasticimetre enregistreur,” 211 (1940), 548, written with E. Joumier; and “Influence de la vitesse sur la forme descycles couple-torsion d’un metal etudie a l’etat visqueux. Hysteresigraphe de torsion a enregistrement photographique,” 214 (1942), 415, written with C. Crussard.

Papers published in the Revue de métallurgie include “contribution des aciers au nickel,” 11 (1914), 841; “Dilatometre differentiel enregistreur,” 14 (1917), 610; “Remarques et observations concernant les phenomenes detrempe des aciers,” 18 (1921), 428, written with A. Portevin, “Nouvelles applications du pyrometre Á dilatation Á l’analyse thermique des alliages,” 19 (1922), 546; “Dilatomètre differential Á enregistrement mecanique,” 23 (1926), 92; “Henry Le Chatelier et l’ organisation scientifique des usines,” 34 (1937), 87; and “Les proprietes mecaniques secondaires. Frottement interne. Relaxation visqueuse. Réactivité. Coefficient de Poisson,” 40 (1943)., 289.

Papers that appeared elsewhere are “Applications desalliages spéciaux Á la pyrométrie,” in Chaleur et industrie, spec. no. (July 1923); “A Dilatometric Study of the Transformations and Thermal Treatment of Light Alloys of Aluminium,” in Journal of the Institute of Metals, 30 (1923), 329, written with “A. Portevin; “A Dilatometric Study of Some Univariant Two-Phase Reactions,” ibid., 42 (1929), 337, written with A. Portevin and X. Waché; “L’analyse dilatometrique des materaux et ses recents progres,” in Revue des aciers speciaux, 3; “Nouvelles recherches sur la corrosion intercristalline des ferronickels chromes,” in Metaux et corrfosion, 12(Feb. 1937), 23; “L’oeuvre metallurgique de Ch. Ed. Guillaume: L’etude et les applications des ferronickels,” in Brochure sur la vie et l’oeuvre de Charles Edouard Guillaume, p. 25; “Nouveaux alliages dutype elinvar pour spiraux de chronometres, “in annalles de chronometrie, 7 (1937), 259, written with X. Waché and A. Villachon; “Étude de la corrosion seche des metaux au moyen d’ une thermobalance, “in,” in Bulletin. Societe chimique de France, 5th ser., 10 (1943), 41, written with X. Waché and R. de la Tullaye; and “Nouvelles etudes dilatometriques des mineraux,” in Bulletin de la Societe Francaise de mineralogie, 66 (1943), 43, written with A. Portevin.

Geogres Chaudron