Hardness Hardness Hardness is a measure of the resistance to localized plastic deformation induced by either mechanical indentation or abrasion. Some materials (e.g. metals) are harder than others (e.g. plastics, wood). Macroscopic hardness is generally characterized by strong intermolecular bonds, but the behavior of solid materials under force is complex; therefore, there are different measurements of hardness: "scratch hardness", "indentation hardness", and "rebound hardness". Hardness is dependent on ductility, elastic stiffness, plasticity, strain, strength, toughness, viscoelasticity, and viscosity. Common examples of hard matter are ceramics, concrete, certain metals, and superhard materials, which can be contrasted with soft matter. There are three
Walter Janka exile in Mexico, where together with Paul Merker and Alexander Abusch he founded the "Free Germany" (""Freies Deutschland"") movement. In Mexico he ran the publishing business "El Libro Libre", which also employed the exiled German writer Anna Seghers. In 1946 Janka took on the leadership of the Mexican section of the German Communist party (KPD). After the end of the Second World War Janka returned, in April 1947, to what was Soviet occupation zone, later to become German Democratic Repbulic in 1949. In 1947 he married his long-standing partner, a translator called Charlotte (Lotte) Scholz. The couples' two children, André