Superior strength-plasticity synergy in a heterogeneous lamellar Ti_(2)AlC/TiAl composite with unique interfacial microstructure

Improving the plasticity of TiAl alloys at room temperature has been a longstanding challenge for the de-velopment of next-generation aerospace engines.By adopting the nacre-like architecture design strategy,we have obtained a novel heterogeneous lamellar Ti_(2)AlC/TiAl composite with superior strength-plasticity synergy,i.e.,compressive strength of∼2065 MPa and fracture strain of∼27%.A combination of micropil-lar compression and large-scale atomistic simulation has revealed that the superior strength-plasticity synergy is attributed to the collaboration of Ti_(2)AlC reinforcement,lamellar architecture and heteroge-neous interface.More specifically,multiple deformation modes in Ti_(2)AlC,i.e.,basal-plane dislocations,atomic-scale ripples and kink bands,could be activated during the compression,thus promoting the plas-tic deformation capability of composite.Meanwhile,the lamellar architecture could not only induce sig-nificant stress redistribution and crack deflection between Ti_(2)AlC and TiAl,but also generate high-density SFs and DTs interactions in TiAl,leading to an improved strength and strain hardening ability.In addi-tion,profuse unique Ti_(2)AlC(1¯10¯3)/TiAl(111)interfaces in the composite could dramatically contribute to the strength and plasticity due to the interface-mediated dislocation nucleation and obstruction mecha-nisms.These findings offer a promising paradigm for tailoring microstructure of TiAl matrix composites with extraordinary strength and plasticity at ambient temperature.

Microstructure Characteristics and Corrugation Interface Behavior of Al/Mg/Al Composite Plate Rolled Under Large Strain

Traditional rolled(TR)aluminum(Al)/magnesium(Mg)/aluminum(Al)composite plates have many bottlenecks such as multiple passes,low interlaminar strength,and weak mechanical properties.In this paper,the hard-plate rolling(HPR)method was used to prepare Al/Mg/Al composite plates under a single pass reduction of 60%.The results show that the ultimate tensile strength(UTS)of the composite plate obtained by hard-plate rolling is 262.3 MPa,and the percentage of total elongation at fracture(At)is 12.3%,which is 31.6%and 37.4%higher than that of the traditional rolling,respectively.It is attributed to the unique corrugated interlocking structure of the interface of the composite plate caused by hard-plate rolling.The shear texture produced by the Mg plate weakens the strong-basal texture.At the same time,the strong basal slip and the large amount of energy stored in the deformed grains provide favorable conditions for dynamic recrystallized(DRX)nucleation.The microstructure is deeply refined by DRX,and the strength and plasticity of the composite plate are improved synchronously.It provides scientific guidance for the development of high-performance lightweight composite plates and the research on hard-plate rolling technology and also has good industrial production and application potential.