French metallurgists

Léon Alexandre Guillet (11 July 1873 – 9 May 1946) was a French metallurgist who studied the properties of metal alloys and developed martensitic and austenitic stainless steels. He served as a professor of metallurgy at the École Centrale Paris where he was a director from 1923 and played a key role in putting materials research on a scientific footing.
Guillet was born in Saint Nazaire (Loire Atlantique) and in 1894 he went to the school of art and manufacture where he met Henri Le Chatelier who guided him. His doctoral thesis was on aluminium alloys and the work was done at Dion-Bouton and at Le Chatelier's laboratory in the Ecole des Mines. He then became a consultant at Dion-Bouton and worked with several companies. In 1906 he went to teach metallurgy and became a full professor in 1908 and worked there until 1942 while also consulting in the industry. In 1923 he became director of the school of arts and manufacture where he brought major changes including a foundation in scientific theories in engineering. During World War I he was involved in the design and manufacture of artillery shells. During World War II, in 1939, he was again put in charge of naval artillery at the Ruelle Foundry in Angoulême as honorary artillery lieutenant-colonel. Guillet published his major metallurgical works including Traité de métallurgie génerale (1922), Les méthodes d'étude des alliages métalliques (1923), and Trempe, recuit, revenue (2 volumes, 1928–1931). He examined steels made with nickel, manganese, chromium, tungsten, as well as copper and aluminium alloys. He examined the heat treatment of alloys.Guillet was elected to the Academy of Sciences in 1925, proposed by Le Chatelier. Guillet married Marie Béatrice Edwidge Soulier in 1898 and they had a daughter and a son, Léon Pierre Adolphe Guillet (1908–1991), who also became a metallurgist.

Jules Henri Debray (26 July 1827, in Amiens – 19 July 1888, in Paris) was a French chemist.
In 1847 he began his studies at the École Normale Supérieure in Paris, and several years later became an instructor at the Lycée Charlemagne (1855). From 1875 onward, he taught classes in chemistry at the École Normale Supérieure, where in 1881 he succeeded Henri Étienne Sainte-Claire Deville as professor of chemistry.He is best remembered for his collaborative research with Sainte-Claire Deville involving the properties of platinum metals, in particular, the melting of platinum and its alloys. Their process for melting platinum remained the chosen method until induction furnaces became available decades later. In 1860, the two scientists were the first to melt an appreciable quantity of iridium.During his career, Debray served as an assayer for the Bureau de Garantie of Paris, was vice-president of the Société d'Encouragement pour l'Industrie Nationale and was a member of the Académie des sciences.

Georges Augustin Albert Charpy (1 September 1865 – 25 November 1945) was the French scientist who created the Charpy impact test. He attended École Polytechnique from 1885 to 1887 and graduated with a degree in Marine Artillery. In 1887 he became a professor at École Monge. In 1892 he published his physics thesis. In 1920 he became a professor of metallurgy at École Nationale Supérieure des Mines de Paris. In 1922 he became the professor of general chemistry at École Polytechnique.