1.Introduction.Ni-Mn-X(X=Ga,In,Sn,or Sb)Heusler alloys have versatile properties[1-4],such as shape memory effect[1],superelastic-ity[5],magnetocaloric effect[3],elastocaloric effect[6],and even multicaloric effect[7]...1.Introduction.Ni-Mn-X(X=Ga,In,Sn,or Sb)Heusler alloys have versatile properties[1-4],such as shape memory effect[1],superelastic-ity[5],magnetocaloric effect[3],elastocaloric effect[6],and even multicaloric effect[7],that indicate their potential for use in actu-ators,sensors,micropumps,energy harvesters,and solid-state re-frigeration[8-10].Among the alloys,Ni-Mn-Sn-based alloys are environment-friendly and cost-effective[6,7,11],and hence,they have received widespread attention.展开更多
The superelasticity and elastocaloric effect(eCE)in N-free Ti-Nb-Zr-Ta alloy and 0.6N(at.%)-doped Ti-Nb-Zr-Ta alloy were comparatively studied.It was found that nitrogen doping played roles in elevating β→α transit...The superelasticity and elastocaloric effect(eCE)in N-free Ti-Nb-Zr-Ta alloy and 0.6N(at.%)-doped Ti-Nb-Zr-Ta alloy were comparatively studied.It was found that nitrogen doping played roles in elevating β→α transition temperature,refining grain sizes,homogenizing microstructure and altering dominant texture index.The N-free Ti-Nb-Zr-Ta alloy exhibited a temperature change of +6.7/−6.5 K during load-ing/unloading processes in the first superelastic cycle,but gradually decreased to+5.7/−5.2 K in 200th cycle owing to the accumulation of newly codirectional dislocation lines and the following single-system dislocation slip during cyclic tests.By contrast,the N-doped alloy showed a lower initial temperature change of+3.7/−3.1 K but increased to+4.6/−4.1 K in 200th cycle due to the extra caloric effect generated from nanoscale O′phase to α″phase which experienced reorientation to favorable variants in early cycles.Residual α″phase laths derived from stress-induced martensitic transformation(SIMT)appeared in both alloys after tensile cycles.The phase interface between β and α″phase was determined to behave a terraced shape,a type of interface compromising the reversible martensitic transformation(MT)and stabilization of martensite phase.The amount of nanodomains(O′phase)in regions situated at a distance from martensite significantly increased after cycles in both alloys,which accounted for the quickly reached stable superelastic deformation and much narrower hysteresis after the first cycle.Therefore,in light of the reproducibility and reversibility of elastocaloric performance in practical application,N-doped β-Ti shape memory alloys(SMAs)are promising candidate materials.展开更多
The 5.0 vol.%GNP/2024Al composites were prepared by accumulated shear deformation combined with heat treatment,i.e.the thermomechanical treatment(TMT).The results showed that homogeneous distributed GNPs that aligned ...The 5.0 vol.%GNP/2024Al composites were prepared by accumulated shear deformation combined with heat treatment,i.e.the thermomechanical treatment(TMT).The results showed that homogeneous distributed GNPs that aligned along the plastic deformation direction were obtained by six-pass drawing in the solution heat treatment state.The introducing of high-density dislocations in Al matrix by multiple drawing resulted in enhanced nucleation of precipitates and subsequent uniform growth during ageing.Consequently,ultra-strength GNP/2024Al composites,with yield and ultimate tensile strength 482 and571 MPa,respectively,were achieved.The high strength was attributed to homogeneous dispersion of undamaged GNPs,fine and dispersed precipitations and work-hardening effect.This work demonstrated that TMT could act as a feasible strategy for preparing high-performance GNP/Al composites.展开更多
基金supported by the National Key R&D Pro-gram of China(No.2022YFB3805701)National Natural Science Foundation of China(NSFC)(No.52371182,51701052,52192592,52192593)+1 种基金Young Elite Scientists Sponsorship Program by CAST(No.2019QNRC001)the Heilongjiang Touyan Innovation Team Program.
文摘1.Introduction.Ni-Mn-X(X=Ga,In,Sn,or Sb)Heusler alloys have versatile properties[1-4],such as shape memory effect[1],superelastic-ity[5],magnetocaloric effect[3],elastocaloric effect[6],and even multicaloric effect[7],that indicate their potential for use in actu-ators,sensors,micropumps,energy harvesters,and solid-state re-frigeration[8-10].Among the alloys,Ni-Mn-Sn-based alloys are environment-friendly and cost-effective[6,7,11],and hence,they have received widespread attention.
基金financially supported by the National Key R&D Program of China(No.2022YFB3805701)the National Natural Sci-ence Foundation of China(NSFC)(No.52371182)the Provincial Natural Science Foundation of China(Grant Number YQ2024E014).
文摘The superelasticity and elastocaloric effect(eCE)in N-free Ti-Nb-Zr-Ta alloy and 0.6N(at.%)-doped Ti-Nb-Zr-Ta alloy were comparatively studied.It was found that nitrogen doping played roles in elevating β→α transition temperature,refining grain sizes,homogenizing microstructure and altering dominant texture index.The N-free Ti-Nb-Zr-Ta alloy exhibited a temperature change of +6.7/−6.5 K during load-ing/unloading processes in the first superelastic cycle,but gradually decreased to+5.7/−5.2 K in 200th cycle owing to the accumulation of newly codirectional dislocation lines and the following single-system dislocation slip during cyclic tests.By contrast,the N-doped alloy showed a lower initial temperature change of+3.7/−3.1 K but increased to+4.6/−4.1 K in 200th cycle due to the extra caloric effect generated from nanoscale O′phase to α″phase which experienced reorientation to favorable variants in early cycles.Residual α″phase laths derived from stress-induced martensitic transformation(SIMT)appeared in both alloys after tensile cycles.The phase interface between β and α″phase was determined to behave a terraced shape,a type of interface compromising the reversible martensitic transformation(MT)and stabilization of martensite phase.The amount of nanodomains(O′phase)in regions situated at a distance from martensite significantly increased after cycles in both alloys,which accounted for the quickly reached stable superelastic deformation and much narrower hysteresis after the first cycle.Therefore,in light of the reproducibility and reversibility of elastocaloric performance in practical application,N-doped β-Ti shape memory alloys(SMAs)are promising candidate materials.
基金the financial supports from National Key R&D program of China(Grant Number2017YFB0703103)Guangdong Province Key Area R&D Program(Grant Number 2019B010942001)Heilongjiang Touyan Team。
文摘The 5.0 vol.%GNP/2024Al composites were prepared by accumulated shear deformation combined with heat treatment,i.e.the thermomechanical treatment(TMT).The results showed that homogeneous distributed GNPs that aligned along the plastic deformation direction were obtained by six-pass drawing in the solution heat treatment state.The introducing of high-density dislocations in Al matrix by multiple drawing resulted in enhanced nucleation of precipitates and subsequent uniform growth during ageing.Consequently,ultra-strength GNP/2024Al composites,with yield and ultimate tensile strength 482 and571 MPa,respectively,were achieved.The high strength was attributed to homogeneous dispersion of undamaged GNPs,fine and dispersed precipitations and work-hardening effect.This work demonstrated that TMT could act as a feasible strategy for preparing high-performance GNP/Al composites.
