This project explores a completely new and highly novel paradigm, invented by the PI, for the creation of new materials that exhibit practically-important mechanical properties far in excess of those exhibited by any previously-known materials. Examples of such properties are stiffness (the ability to resist deformation under load) and damping (the ability to dissipate vibration and sound). Preliminary theoretical studies by the proposers indicate the great potential of this approach, and their preliminary experimental studies have shown that a research sample created following this new paradigm exhibits stiffness ten times that of diamond, the previously-known stiffest material. The paradigm involves embedding a material that would be unstable by itself in another, stable material and carefully tuning the properties of the two materials so that the resulting combined material exhibits the desired extreme properties. The present research is directed toward providing the necessary further theoretical and experimental scientific advances needed to confirm that such novel materials do indeed have the potential for wide utility. This research is important because the paradigm involved has the greatest potential of all existing approaches for dramatically improving multiple mechanical properties of materials. It has potential impact far beyond the specific work to be carried out, because the idea of employing constrained instability could well lead to regimes previously inaccessible in many other fields. The work also has great educational importance, in that it demonstrates to students the potential for achieving the seemingly impossible by critical outside the box thinking.
TECHNICAL DETAILS The proposed work builds on recent theoretical and experimental breakthroughs by the proposers which showed that composite materials containing a negative-stiffness phase: (1) are theoretically predicted to have stiffness, damping and piezoelectric properties far exceeding those of any known material; (2) can be proved to be stable overall, and thus can evade the bounds on overall material response that have been believed for the past half-century to limit composite material performance, since these bounds assume all component materials must have positive stiffnesses; (3) can be fabricated using partially-constrained phase-transforming ceramic inclusions and can be shown in laboratory testing to exhibit stiffness ten times that of diamond and damping greatly exceeding that of either phase. The research involves close coordination of theoretical stability and composite material behavior analyses with laboratory fabrication and testing. The goals of the project are to extend the robustness and operational range, in strain, temperature and stability, of the proposers? preliminary laboratory composite materials comprised of partially-constrained phase-transforming ceramic inclusions in a metal matrix, and to provide convincing additional theoretical and experimental confirmation of the validity and utility of this novel material creation approach. This research is important, timely and potentially transformational because it involves a completely new and novel material creation paradigm, and the PIs are unaware of any other material creation paradigm having such potential for dramatic improvement in material properties, and especially such important, diverse and numerous properties as stiffness, damping and piezoelectricity (and very possibly several additional ones). It is thought that this EAGER support will result in convincing theoretical and experimental evidence that the materials created can be utilized under the conditions that would give them wide applicably. The project also has multiple important educational aspects: broadly, it will teach students the potential for achieving the seemingly impossible by critical outside the box thinking. Furthermore, the undergraduate and graduate students working directly on the project will learn completely novel research techniques involved with creating materials employing the idea of tuned constrained metastability.
