Phase-Transitions at High, Very High, and Very Low Temperatures upon Nano-Indentations: Onset Forces and Transition Energies

This paper describes the phase-transition energies from published loading curves on basis of physically deduced FN = k-h3/2 law that does not violate energy by assuming h2 instead, as still do ISO-ASTM 14,577 standards. is valid for all materials and “one-point indentation” temperatures. It detects initial surface effects kink-unsteadiness. Why important? The mechanically induced phase-transitions form polymorph interfaces with increased risk crash nucleation example at pickle forks airliners. After our crashing risk, nucleated within microscopic polymorph-interfaces via pre-cracks, had finally appeared (we presented images (5000×) a model system), 550 airliners were once grounded 18 months due to such pre-cracks their (connection device wing body). These previously complained (semi)yearlycheckups But higher compliance against phase- transitions must be developed everybody’s safety, most easily checking nanoindentations, using correct analyses. Unfortunately, non-physical analyses, based after incredible exponent 2 h versus curve are enforced standards cannot detect phase-transitions. propagate force, applied penetrating cone or pyramid shall used depth formation, but also in part pressure indenter environment. However, remaining (that was consumed migrations, etc.) always elastic modulus detection routine. That severely violates energy-law! Furthermore, now analyzed contain onsets information, because these old-fashioned authors innocently (?) (of course correct) experimental curves. follow ever relation law. Nevertheless, stubbornly assume h2instead h3/2 according an Oliver-Pharr publication 1992 textbooks. present work contributes understanding temperature dependence under mechanical load, only aviation space flights, which important. physical calculations use exclusively regressions pure algebra (no iterations, no fittings, simulations) series straightforward steps correcting unavoidable axis cuts linear branches above equation exhibiting sharp kink unsteadiness onset phase transitions. test Molybdenum Al 7075 alloy. strictly relation. Full work, conversion per unit show reliable overall comparable order magnitude values increase 150°C (Al 7075) 980°C (Mo) when considering different hardnesses penetration depths. turns out how much normalized endothermic decreases upon increase. For known 1000°C indentation we provide reason changes minor degree caused thermal expansion. results up 170°C successfully compared. alloy checked liquid nitrogen cooling (77 K). gives two one very prominent exothermic transition particularly high energy. reveals epochal novelties. requiring (already seen 20°C above) 77 K shortly start second (sharply 19.53 N force) followed strongly producing losing) energy-content. Both processes totally unexpected. produced than required previous conversions. profits inability further formation third obtained 70°C above. possible cold crystal can longer support events supports ones. load unprecedented expected before. While energetic unusual understandable (there means produce lower temperatures). exothermicphase-transition production new modification negative content (less ambient polymorph) low event here earth. leads global thinking promises important applications. transformed material less thermodynamic standard zero energy-content And it reached there possibility left phase-transition. Such zero-energy-content should isolated, appropriate equipment. Their properties investigated chemists, crystallographers, physicists cosmological reasons. could will require despite (higher stability!) survive temperatures pressures earth, know negative-energy-content arbitrary zeros At first have study far go keeping them stable. Thus, apparently never before considered result opens search polymorphs can, course, heating. Various applications including cosmology flight explorations profiting it.