Complex of mechanical properties of aluminium based intermetallic compounds and their deformation and fracture features at the nanometre and micrometre scales.

First in the identical loading conditions the mechanical parameters such as Young's modulus Е, microhardness HV and nanohardness Hh, plasticity characteristics dH »dA, yield stress s0,2, temperature range of ductile-brittle transition, fracture toughness K1c, of intermetallics on the basis of aluminium, wich were absent in reference books till now, and the features of their deformation and destructions on nanо- and microlevels are determined.

All of investigated Al-based intermetallics, such as Al3Ti, Al3Zr, Al3Fe, Al2CaSi2, with the exception of Al4Ca, revealуed high rigidity and on the values of Young's modulus approach the ceramic materials. On the level of strength (HV, s0,2) and tendency to the deformation work-hardening it is possible to dispose the investigated intermetalics in a such rank: Al4Ca, Al2CaSi2 ® Al3Ti, Al3Zr ® Al3Fе.

All investigational intermetallics, including Al3Ti, Al3Zr, Al3Fe, Al4Ca and Al2CaSi2, are found low-plastic materials for which the plasticity characteristic dH appears less then critical value dH = 0,9, that testifies to their tendency to brittle fracture at loading in the standard conditions of tension and bending. On the level of plasticity the intermetallics on the base of aluminium are comparable with some natural minerals (for example, CaCO3), occupying intermediateposition between bcc-metals and ceramic compounds. All of investigated intermetallics of aluminium have very low fracture toughness K1c, which on an absolute value appears comparable with oxygen-free ceramics (for example, Cr7C3). For intermetallic Al4Ca this parameter appears even less than, that for covalently crystals (for example, Si) and glass.

The results of the present study are important for development the newest technologies of manufacturing of modern lightweight alloys, in particular, high-strength aluminium alloys and foam aluminium, optimization of their composition and structure, prognostications of mechanical behaviour in the real exploitation conditions on-loading. Physical representations are developed in area of theory of deformation and destruction at introduction of rigid pyramidal indentor in low-plastic intermetallic compounds in the conditions of elastic-plastic contact at nanо- and microlevels with the use of modern physical and mathematical models of hardness, which allow to research the features of deformation of the intermetallic materials on-loading. These results are important both for the current basic research and for application in engineering practice.