The Static And Dynamic Mechanical Properties Of New Structural Zirconium Alloys

Zirconium and zirconium alloys have great potential in aerospace field due to their exceptional physic-chemical properties such as corrosion resistance,anti-irradiation,the small neutron absorption area,low density,small expansion coefficient,and so on.Moreover,zirconium powder is highly combustible,which is the desired properties of structural material for military use.It is very necessary to prepare and study the new structural zirconium alloys with high strength to widen the application field.In this paper,ZrTi binary alloys,ZrTiFe ternary alloys and ZrTiAlV quaternary alloys were designed and obtained.Effect of chemical compositions and microstructures on the static and dynamic mechanical properties of new structural zirconium alloys was systemically investigated.The main results and conclusions are as follows:In the quasi static tests,ZrTiAlV alloy exhibited the highest yield strength and tensile strength,whereas ZrTi alloy exhabited the lowest strength but the best ductility.In the dynamic compression tests,ZrTiAlV alloy showed a compressive strength greater than1100MPa,ZrTi alloy reaching 1057MPa,while ZrTiFe alloy showed the 930MPa compressive strength.As the strain rate increased from 2000s^-1 to 3000s^-1,the dynamic compressive strength increased which reflected the strain hardening effect.At the strain rate of 3000s^-1,ZrTiAlV alloy absorbed most energy before failure,and the optimal compressive strength was obtained,i.e.,1200MPa and 309MJ·m^-3,respectively,while ZrTi alloy reached the highest critical fracture strain of 26.92%.Three kinds of typical microstructures of the ZrTiFe alloy were obtained by controlling the heat treatment process.The static and dynamic mechanical properties of the alloy were found to be connected with different microstructures.The results showed that all these microstructures were comprised of?and?phase.Bimodal microstructure exhibited the highest strength,equiaxed microstructure the best ductility,while the mechanical properties of basketweave structure reached the optimum combination.In the dynamic compression tests,all these microstructures showed the strain hardening effect.At the strain rate of 3000s^-1,bimodal microstructure had the optimal compressive strength of 1116MPa,while equiaxed microstructure obtained the highest critical fracture strain of 30.28%.Necking phenomenon was observed in static tensile speciments of the three alloys,which reflected the ductile fracture mode,characterized by dimples and tearing ridges.The macro crack at 45°angle with the compression axis was observed in dynamic compressive specimens.The failure mechanism was facilitated by initiation and propagation of adiabatic shear bands and cracks induced by adiabatic shear bands.