Computation of concentrations of characteristic atoms of alloys in BCC structure

In this paper, taking Nb-Mo alloy system as an example, the equations of concentration of characteristic atoms of alloys in BCC structure were obtained on the basis of the idea of systematic science of alloys and the number of coordination atoms. The concentrations of characteristic atoms in B2-NbMo type ordered alloys were calculated as functions of ordering degree（s） and composition Xuo. When S=Smax, the concentrations of characteristic atoms of stoichiometric B2-NbMo intermetallic compound are equal to that of alloys, that is, X8^Nb = 0.5 at, X0^Mo= 0.5 at. As ordering degree decreases, characteristic atoms A8^Nb and A0^Mo of B2-NbMo type ordered alloy split. And the degree of splitting of characteristic atoms increases with the ordering degree decreasing. Therefore, disordered alloys and various types of ordered alloys can be designed.

Derivation and application of concentration formula of alloy genes of DO_3-type in BCC alloy systems

Taking Ta–W alloy system as an example, the concentration formulae of alloy genes of DO3-type alloys in BCC structures were derived on the basis of the theory of alloy genes and the number of coordination atoms. The concentrations of alloy genes of DO3-TaW3 and DO3-Ta3W ordered alloys were calculated as functions of composition xW and ordering degree （s）. When s=smax, the concentrations of alloy genes of stoichiometric DO3-TaW3 compound are equal to those of alloys, that is, x8^Ta=0.25（at）,x4^W=0.5（at）,x8^W=0.25（at）The concentrations of alloy genes of stoichiometric DO3-Ta3W compound are also equal to those of alloys, that is,x0^Ta=0.25（at）,x4^Ta=0.5（at）,x0^W=0.25（at）. As ordering degree decreases, alloy genes of DO3-TaW3 and DO3-Ta3W ordered alloys will split. And the degree of splitting of alloy genes increases with the ordering degree decreasing. The atomic states and properties of DO3-TaW3 and DO3-Ta3W ordered alloys were calculated as a function of composition xW. The reason was pointed out that preparation of DO3-TaW3 and DO3-Ta3W intermetallic compounds is difficult due to small differences in their cohesive energies. It will provide theoretical guidance for the scientific designation to new candidate for ultra- high-temperature materials in areo-engine applications.

Assessment of Similitude Behavior in Natural Frequencies of Printed Turbine Blade

Improving structures involves comparing old and new designs on a key parameter.Calculating the percent change in performance is a method to assess.This paper proposes a cost-effective analogy by generating replicas of additive manufactured aluminum alloy(Al Si10Mg)body-centered cubic lattice(BCC)based turbine blade(T106C)with the same in poly-lactic acid(PLA)material and their comparison in the context of percent change for natural frequencies.Initially,a cavity is created inside the turbine blade(hollow blade).Natural frequencies are obtained experimentally and numerically by incorporating BCC at 50%and 80%of the cavity length into the hollow blade for both materials.The cost of manufacturing the metal blades is 90%more than that of the PLA blades.The two material blade designs show a similar percentage variation,as the first-order mode enhancs more than 5%and the second-order mode more than 4%.To observe the behavior in another material,both blades are analyzed numerically with a nickel-based U-500 material,and the same result is achieved,describing that percent change between designs can be verified using the PLA material.

Remarkably high fracture toughness of HfNbTaTiZr refractory high-entropy alloy

High-entropy alloys(HEAs)with face-centered cubic(FCC)phase such as CoCrFeMnNi or CoCrNi generally exhibit ultra-high fracture toughness but relatively low strength.In contrast,body-centered cubic(BCC)HEAs often display higher strengths,but the few reports on fracture toughness measurement demonstrate low toughness values.Here we show that the BCC HfNbTaTiZr refractory HEA,which possesses a combination of high strength,good tensile ductility and excellent high-temperature properties,also exhibits a remarkably high fracture toughness.By using the"single specimen"compliance method for J-integral measurement according to the ASTM E1820–17 standard,its fracture toughness K_(JIC)was experimentally determined to be 210 MPa m^(1/2),which renders this HEA among the toughest metallic materials.The excellent damage tolerance makes the HEA promising for applications as high-temperature structural materials such as in aerospace field.

Development of Ti-V-Cr-Mn-Mo-Ce high-entropy alloys for high-density hydrogen storage in water bath environments

The V-based body-centered cubic(BCC)-type hydrogen storage alloys have attracted significant attention due to their high theoretical hydrogen storage capacity of3.80 wt%.However,their practical application faces challenges related to low dehydriding capacity and poor activation performance.To overcome these challenges,a BCC-type Ti-V-Cr-Mn-Mo-Ce high-entropy alloy(HEA)with an effectively dehydriding capacity of 2.5 wt% above 0.1 MPa was prepared.By introduction of Mo and conducting heat treatment,the precipitation of Ti-rich phase in HEA was successfully suppressed,resulting in improved compositional uniformity and dehydriding capacity.Consequently,the effective dehydriding capacity increased significantly from 0.60 wt% to 2.50 wt% at 65℃,surpassing that of other types of hydrogen storage alloys under the same conditions.Moreover,the addition of 1 wt%Ce enabled initial hydrogen absorption at 25℃ without the need for activation at 400℃.Furthermore,Ce doping reduced the dehydriding activation energy of the Ti-V-Cr-Mn-Mo-Ce HEA from 52.71 to 42.82 kJ·mol^(-1)Additionally,the enthalpy value of dehydrogenation decreased from 46.89 to 17.96 k J·mol^(-1),attributed to a decrease in the hysteresis factor from 0.68 to 0.52.These findings provide valuable insights for optimizing the hydrogen storage property of HEA.