Hydrogen storage properties of (Ti0.85Zr0.15)1.05Mn1.2Cr0.6V0.1M0.1 (M=Ni, Fe, Cu) alloys easily activated at room temperature

The(Ti_(0.85)Zr_(0.15))_(1.05)Mn_(1.2)Cr_(0.6)V_(0.1)M_(0.1)(M=Ni, Fe, Cu) alloys with a single C14-type Laves phase have been fabricated by arc melting. They are able to be easily activated by one hydrogen absorption and desorption cycle under 4 MPa hydrogen pressure and vacuum at room temperature. Partial substitution of M for Mn results in the increase of hydrogenation and dehydrogenation capacities in an order of Ni Fe Cu. M elements increase the absorption and desorption plateau pressure in an order of(Ti_(0.85)Zr_(0.15))_(1.05)Mn_(1.2)Cr_(0.6)V_(0.1)Cu_(0.1)(Ti_(0.85)Zr_(0.15))_(1.05)Mn_(1.2)Cr_(0.6)V_(0.1)Fe_(0.1)(Ti_(0.85)Zr_(0.15))_(1.05)Mn_(1.2)Cr_(0.6)V_(0.1)Ni_(0.1). The(Ti_(0.85)Zr_(0.15))_(1.05)Mn_(1.2)Cr_(0.6)V_(0.1)Cu_(0.1) alloy has reversible hydrogen capacities of 1.81 wt% at 273 K and 1.58 wt% at 318 K with formation enthalpy(ΔH_(ab)) of-20.66 kJ mol~(-1) and decomposition enthalpy(ΔH_(de)) of 27.37 kJ mol~(-1). The differences in the hydrogen storage properties can be attributed to the increase of the interstitial size for hydrogen accommodation caused by the increase of unit cell volumes in the order of(Ti_(0.85)Zr_(0.15))_(1.05)Mn_(1.2)Cr_(0.6)V_(0.1)Ni_(0.1)(Ti_(0.85)Zr_(0.15))_(1.05)Mn_(1.2)Cr_(0.6)V_(0.1)Fe_(0.1)(Ti_(0.85)Zr_(0.15))_(1.05)Mn_(1.2)Cr_(0.6)V_(0.1)Cu_(0.1).     

Effect of Zr addition on the stability of precipitated Laves phase and mechanical properties of Fe–Cr–Al-based alloys at high temperatures

The effect of a small amount of Zr addition on the temperature-dependent stability of Laves phase particles and mechanical properties of Fe-13.5Cr-4.73Al-2.07Mo-(0.34–0.5)Nb-(0.65–0.98)Ta-(0–0.33)Zr (wt. %) ferritic alloys was investigated in the present study. The designed alloy ingots were hot-rolled, aged at 1073 ?K for 24 ?h, and then re-treated at 1273 ?K, 1323 ?K, 1373 ?K, and 1473 ?K for 1 ?h, respectively. It was found that the Zr addition could not only stabilize the Fe₂M Laves phase (M ?= ?Mo,Nb,Ta,Zr) to a much higher temperature, but also induce the formation of stable Fe₂₃Zr₆ phase. The high-temperature (HT) microstructural stability of the alloys significantly was improved, as evidenced by the fact that a certain amount (0.66–1.19%) of precipitates (Fe₂M, Fe₂₃Zr₆, and core(Fe₂₃Zr₆)-shell(Fe₂M)-structured particles) with an appropriate size (～1.0 ?μm) uniformly distributed in the ferritic matrix even after being re-treated at 1473 ?K. Particularly, the formation of core-shell-structured particles at HTs was studied from the viewpoint of both solid solubility and diffusion coefficient of M in the matrix. All these aged alloys exhibited prominent mechanical properties at both room and elevated temperatures, showing high yield strength with σ_YS ?= ?490–560 ?MPa at room-temperature and σ_YS ?= ?80–85 ?MPa at 1073 ?K. The strengthening effect was further discussed in light of various strengthening mechanisms, and the calculated strength are in good agreement with the experimental results.     

Study on the hydrogen storage property of (TiZr0.1)xCr1.7-yFeyMn0.3 (1.05

Jigang Li  Li Xu  Xiaojing Jiang  Xingguo Li 《自然科学进展(英文版)》2018,28(4):470-477

Reversible hydrogenation of AB2-type Zr–Mg–Ni–V based hydrogen storage alloys

The development of hydrogen energy is hindered by the lack of high-efficiency hydrogen storage materials. To explore new high-capacity hydrogen storage alloys, reversible hydrogen storage in AB₂-type alloy is realized by using A or B-side elemental substitution. The substitution of small atomic-radius element Zr and Mg on A-side of YNi₂ and partial substitution of large atomic-radius element V on B-side of YNi₂ alloy was investigated in this study. The obtained ZrMgNi₄, ZrMgNi₃V, and ZrMgNi₂V₂ alloys remained single Laves phase structure at as-annealed, hydrogenated and dehydrogenated states, indicating that the hydrogen-induced amorphization and disproportionation was eliminated. From ZrMgNi₄ to ZrMgNi₂V₂ with the increase of the degree of vanadium substitution, the reversible hydrogen storage capacity increased from 0.6 ?wt% (0.35H/M) to 1.8 ?wt% (1.0H/M), meanwhile the lattice stability gradually increased. The ZrMgNi₂V₂ alloy could absorb 1.8 ?wt% hydrogen in about 2 ?h ?at 300 ?K under 4 ?MPa H₂ pressure and reversibly desorb the absorbed hydrogen in approximately 30 ?min ?at 473 ?K without complicated activation process. The prominent properties of ZrMgNi₂V₂ elucidate its high potential for hydrogen storage application.     

Structure and effect of diamagnetism on manganese lithium phosphate glass to cathode materials application

1-x(Li₂O–2P₂O₅)-xMnO₂ glasses where x ?= ?0.2, 0.3 and 0.4 ?mol%, respectively, were synthesized by melted-quenching method. The Mn and P oxidation states and local structures around Mn and P-ions including Mn–O and P–O bonding distances and coordination numbers have been studied via X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS), respectively. XANES results exhibit a coexistence of oxidation state of Mn²⁺ and Mn³⁺ with a mean value of 2.82. Moreover, Mn and P K-edge EXAFS show the Mn–O and P–O bonding distances of approximately 2.083–2.094 ?Å and 1.766–1.774 ?Å, respectively. A paramagnetism was found for all Mn–P glasses. Additionally, the coercive field (H_c) and remnant magnetization (M_r) increased with increasing Mn contents. However, the low specific capacitances are seriously obtained (<40 ?F ?g^?1) suggesting the effect of natural diamagnetism of lithium phosphate based-glass unlike the borate based-glasses which originally exhibit paramagnetism.     

Effect of Ce addition on hot corrosion behaviours of a cast γ′-strengthened Co–Al–W–Mo–Ta–B alloy at 800 ​°C

Hot corrosion behaviours of a novel Co–9Al-4.5W-4.5Mo–2Ta-0.02B alloy doped with 0.01, 0.05, 0.1 and 0.2 ?at% Ce exposed at 800 ?°C in a solution of 75%Na₂SO₄/25%NaCl were investigated. The alloys comprised a coherent γ-Co_SS/γ′-Co₃(Al, W) microstructure (0.01Ce and 0.05Ce alloys) and κ-Co₃(W, Mo) precipitates (0.1Ce and 0.2Ce alloys) at grain boundaries. Hot corrosion kinetics curves demonstrated the parabolic time dependency profile with two stages: the first parabolic stage is within the beginning ～50 ?h corrosion and follows by the second parabolic stage. With an increasing nominal Ce content the weight gain of the alloy significantly decreased from approximately 70.1 ?mg ?cm^?2 (0.01Ce) to 40.8 ?mg ?cm^?2 (0.2Ce) when exposed for 100 ?h. A two-layer corrosion scale formed, and the scale was composed of an outer layer of Co₃O₄ oxide with spinel compounds of CoAl₂O₄, CoWO₄and CoSO₄, and an inner γ/needle-like Co₃W/sulphide layer adhered to the substrate. Heavy spallation of the corrosion scale occurred in the 0.01Ce～0.1Ce alloys, however, spallation was slight in the 0.2Ce alloy. The excellent corrosion resistance of the 0.2Ce alloy could be attributed mainly to the formation of continuous Al₂O₃ lines in the corrosion scale, as well as the prolongation of the incubation period of the corrosion product spallation.     

Composition design of superhigh strength maraging stainless steels using a cluster model

The composition characteristics of maraging stainless steels were studied in the present work investigation using a cluster-plus-glue-atom model. The least solubility limit of high-temperature austenite to form martensite in basic Fe–Ni–Cr corresponds to the cluster formula [NiFe12]Cr3,where NiFe12is a cuboctahedron centered by Ni and surrounded by 12 Fe atoms in FCC structure and Cr serves as glue atoms. A cluster formula [NiFe12](Cr2Ni) with surplus Ni was then determined to ensure the second phase(Ni3M) precipitation,based on which new multicomponent alloys [(Ni,Cu)16Fe192](Cr32(Ni,Mo,Ti,Nb,Al,V)16) were designed. These alloys were prepared by copper mould suction casting method,then solid-solution treated at 1273 K for 1 h followed by water-quenching,and finally aged at 783 K for 3 h. The experimental results showed that the multi-element alloying results in Ni3M precipitation on the martensite,which enhances the strengths of alloys sharply after ageing treatment. Among them,the aged [(Cu4Ni12)Fe192](Cr32(Ni8.5Mo2Ti2Nb0.5Al1V1)) alloy(Fe74.91Ni8.82Cr11.62Mo1.34Ti0.67Nb0.32Al0.19V0.36Cu1.78wt%) has higher tensile strengths with YS?1456 MPa and UTS?1494 MPa. It also exhibits good corrosion-resistance in 3.5 wt% NaCl solution.     

Magnetic properties of Fe3(1−x)Cr3xC alloys

The magnetic properties of Fe_3(1−x)Cr_3xC alloys with x=0.05, 0.1, 0.15, and 0.2, which crystallize in the cementite Fe₃C-type structure with space group Pnma, were investigated by means of magnetization measurements. These alloys show temperature-induced second-order magnetic phase transitions. The Curie temperature (T_c) of these alloys decreases with increasing x. The isothermal magnetic-entropy changes of these alloys were derived from the magnetic isotherms measured with increasing temperature and increasing field. The maximum values of the magnetic-entropy change are about 0.9 and 3.6 J·kg⁻¹·K⁻¹ at T_c =360 K for x = 0.05 in a magnetic field change from 0 to 1 T and 0 to 5 T, respectively.     

Ferromagnetism at 230 K in （Ba0.7K0.3）（Zn0.85Mn0.15）2As2 diluted magnetic semiconductor

We report the ferromagnetism with Cure temperature Tcat 230 K in a new diluted magnetic semiconductor(DMS)(Ba0.7K0.3)(Zn0.85Mn0.15)2As2isostructural to ferropnictide 122 superconductors synthesized via low temperature sintering.Spin is doped by isovalence substitution of Mn2+for Zn2+,while charge is introduced by heterovalence substitution of K1+for Ba2+in(Ba0.7K0.3)(Zn0.85Mn0.15)2As2DMS,being different from(Ga,Mn)As where both spincharge are induced simultaneously by heterovalence substation of Mn2+for Ga3+.The(Ba0.7K0.3)(Zn0.85Mn0.15)2As2DMS shows spontaneous magnetization following T3/2dependence expected for a homogeneous ferromagnet with saturation moment 1.0μB for each Mn atom.     

Improvement in hydrogen storage performance of Mg by mechanical grinding with molten salt etching Ti3C2Clx

Mg-based materials are currently a hot research topic as hydrogen storage materials due to their considerable theoretical hydrogen storage capacity. However, the kinetic performance of hydrogen absorption and desorption of Mg is too slow and requires high temperature, which seriously hinders the application of this material. MXene is a new type of two-dimensional material with significant role in improving thermodynamics and kinetics. In this experiment, a two-dimensional layered MXene containing Cl functional group was prepared by molten salt etching using the Ti-containing MAX phase as the raw material. Then different ratios of Ti₃C₂Cl_x were uniformly dispersed onto the surface of Mg by high energy ball milling. The samples were characterized by hydrogen absorption and desorption kinetics, SEM, XRD, XPS, and DSC to investigate the effect of Ti₃C₂Cl_x on the hydrogen absorption and desorption performance of Mg. The onset hydrogen absorption temperature can be reduced to room temperature and the hydrogen release temperature is reduced by 200 ​°C by doping Ti₃C₂Cl_x. And there is also 5.4 ​wt% hydrogen storage in the isothermal hydrogen absorption test at 400 ​°C. The results of DSC demonstrate that the E_a of Mg+15 ​wt% Ti₃C₂Cl_x was reduced by 12.6% compared to pristine Mg. The ΔH is almost invariable. The results of XPS show that the presence of multivalent Ti promotes electron transfer and thus improves the conversion between Mg²⁺/Mg and H⁻/H. This study provides a guideline for further improving the hydrogen absorption and desorption performance of Mg-based hydrogen storage materials.     

Centimeter-sized Ti-based bulk metallic glass with high specific strength

Based on the quaternary Ti₄₁Zr₂₅Be₂₉Al₅ glassy alloy with a critical diameter of 7 mm reported not long ago, an obvious enhancement of glass-forming ability (GFA) has been realized in this alloy by the addition of Cu element. A series of (Ti₄₁Zr₂₅Be₂₉Al₅)_100?xCu_x (x=0, 2, 5, 7, 9, 11 at%) glassy alloys have been developed and some of them can be cast into one-centimeter diameter fully glassy rods by copper mold suction casting. It has been found that Cu addition could stabilize the liquid phase and suppress the crystallization, resulting in improvement of the GFA of the alloy. The addition of Cu also increases the compressive strength of the alloy and the (Ti₄₁Zr₂₅Be₂₉Al₅)₉₁Cu₉ glassy alloy possesses a specific strength (defined as yield strength/density) of 4.13×10⁵ Nm/kg, which is much higher than most other reported centimeter-sized bulk metallic glasses. The present result suggests that the newly developed (Ti₄₁Zr₂₅Be₂₉Al₅)₉₁Cu₉ glassy alloy is a good candidate for structural applications because of its good glass-forming ability and mechanical properties.     

Highly stable N-containing polymer-based Fe/Nx/C electrocatalyst for alkaline anion exchange membrane fuel cell applications

A cost-effective electrocatalyst with high activity and stability was developed. The Fe-Nx and pyridinic-N active sites were embedded in nitrogen-doped mesoporous carbon nanomaterial by carbonization at high temperature. The electrocatalyst exhibited excellent electrochemical performance for the oxygen reduction reaction, with high onset potential and half-wave potential values (E_onset = 1.10 ?V and E_1/2 ?= ?0.944 ?V) than 20 ?wt % Pt/C catalyst (1.04 and 0.910 ?V). The mass activity of the Schiff base network (SNW) based SNW-Fe/N/C@800° electrocatalyst (0.64 ?mA ?mg^?1 @ 1 ?V) reached about half of the commercial Pt/C electrocatalyst (1.35 ?mA ?mg^?1 @ 1 ?V). The electrocatalyst followed the 4-electron transfer mechanism due to very low hydrogen peroxide yield (H₂O₂ ?< ?1.5%) was obtained. In addition, this electrocatalyst with dual active sites showed high stability during cyclic voltammetry and chronoamperometry measurements. More importantly, the electrocatalyst also demonstrated the power density of 266 ?mW ?cm^?2 in the alkaline anions exchange membrane fuel cell (AEMFC) test, indicating its prospective application for fuel cells.     

Effect of Nb on the corrosion behavior of continuous bulk metallic glass-coated steel wire composites

(Zr_41.2Ti_13.8Cu_12.5Ni₁₀Be_22.5)_100?xNb_x (at%, x=0 and 8) bulk metallic glasses (BMGs) were coated on the surface of Q195 steel wires by a continuous coating process. The potentiodynamic polarization tests of these BMGs were conducted in 3.5wt% NaCl aqueous solution. It is found that the addition of 8at% Nb into Zr_41.2Ti_13.8Cu_12.5Ni₁₀Be_22.5 alloy results in the improvement of corrosion resistance with the pitting potential of ?52 mV, the open circuit potential of ?446 mV, and the corrosion current density of 9.86×10?6 mA/cm2. This may be attributed to that Nb is beneficial to passivate and stabilize Zr and Ti.     

Microstructure and improved mechanical properties of ultrafine-grained Mo-12Si-8.5B (at.%) alloys with addition of ZrB2

Multi-hierarchical Mo-12Si-8.5B-x Zr B_2(x=0,0.5,1.0,1.5,2.5 wt%)alloys consisting of three ultrafine-grained(UFG,0.47–0.81μm)phases of Mo_5Si B_2(T2),Mo_3Si and Mo solid solution(α-Mo)were prepared by mechanical alloying following hot pressing.Microstructure observations showed that the intermetallic phases(Mo_3Si and T2)distributed dispersedly in the continuousα-Mo matrix associated with the homogeneously embedded nanoscaled particles(10–225 nm)in the grain interiors and at the grain boundaries.The Mo-12Si-8.5B-x Zr B_2alloys exhibited monotonically increasing compressive strength to 3.13 GPa with increasing content of Zr B_2,and the fracture toughness increased about 27%and reached at 11.5 MPa m~(1/2)at 1.0 wt%Zr B_2,rendering the Mo-12Si-8.5B-1.0 wt%Zr B_2alloy possessing the best combined mechanical properties of high strength and high toughness.The underlying reason for the superior mechanical properties of the Mo-12Si-8.5B-x Zr B_2alloys is that the dispersedly distributed nanosized particles in the UFG multi-phased-matrix can not only effectively block the dislocation motion to increase the strength but also store the dislocations to increase the strain hardening ability during mechanical deformation.     

Optimization of mechanical properties of Sn-3.8Ag-0.7Cu alloys by the additions of Bi,In and Ti

Bi, In and Ti were added to Sn-3.8Ag-0.7Cu (SAC387) solder alloy to optimize the mechanical performance. The alloying effects of Bi, In and Ti on the microstructure, thermal and mechanical properties of SAC387 based solder alloys were investigated. The results demonstrate that adding 3.5 ?wt % of Bi could refine the microstructure, optimize the thermal properties, and improve the tensile strength. Meanwhile, the ductility of the solder alloys reduced evidently. Adding 2.8 ?wt % of In into SAC387–3.5 ?wt %Bi alloy could increase both the strength and ductility, which is attributed to the beneficial effect of In addition, as adding In could improve the solubility of Bi in the β-Sn matrix. Meanwhile, the melting point was reduced, and the wettability improved with the addition of In. Introducing amounts of Ti into SAC387–3.5 ?wt % Bi-2.8 ?wt % In alloy could further increase the strength. However, the ductility was significantly reduced when 0.8 ?wt % of Ti was added due to the formation of the coarse Ti₂Sn₃ phase. The undercooling was remarkably reduced with the addition of Ti. The nanoindentation tests demonstrate that the hardness increased mainly due to the hardening effect of the Bi addition. Among all the samples prepared, alloy SAC387–3.5 ?wt % Bi exhibited the highest creep resistance at the ambient temperature. Further adding In and Ti into SAC387–3.5 ?wt % Bi alloys reduced the creep resistance of the solder alloys. The mechanism associated with the different mechanical responses is also discussed in this study.     

Eutectic reaction and cored dendritic morphology in yttrium doped Zr-based amorphous alloys

The microalloying effect of yttrium on the crystallization behaviors of (Zr_0.525Al_0.10Ti_0.05Cu_0.179Ni_0.146)_100-x Y_x, and (Zr_0.55Al_0.15-Ni_0.10Cu_0.20)_100-x Y_x (x=0, 0.4, and 1, thus the two alloy systems were denoted as Zr52.5, Zr52.5Y0.4, Zr52.5Y1, and Zr55, Zr55Y0.4, Zr55Y1, respectively) was studied. Transmission electron microscopy (TEM) results suggested that the crystalline phases were different in the two Zr-based alloys and with different yttrium contents. ZrNi-phase and Al₃Zr₅ phase precipitations can be well explained by the mechanisms of nucleation and growth. Al₃Zr₅ phase is mainly formed by a peritectic-like reaction, while ZrNi-phase by a eutectic reaction. The contents of elements Y, Al, and Ti may dominate the reaction types. The orientation relationship between Y₂O₃ particles and Al₃Zr₅ phase is also discussed.     

EPR and UV—vis studies of biomimetic complexes of molybdoenzyme and tungstoenzyme

The biomimetic synthesis and the study of the ca-talysis mechanism of molybdenum and tungsten oxotransfer enzyme have been attracted considerable at-tention for a long time, because the oxotransfer enzymes play an important part in the nitrogen, sulfur and carbon cycles in the biological system[1—4]. With the development of the X-ray crystallography, it is possible to determine the structure of molybdenum and tungsten enzymes. However, due to the complexity and dedicated nature of the protein…     

Microstructure and mechanical properties of TiAl/TiAl joints brazed with a newly developed Ti–Ni–Nb–Zr quaternary filler alloy

A novel Ti–Ni–Nb–Zr quaternary filler alloy with the composition of Ti-(19～25)Ni-(15～25)(Nb ?+ ?Zr) (wt.%) was designed. The filler alloy was composed of (Ti,Nb)ss, (Ti,Zr,Nb)ss ?+ ?(Ti,Zr)₂Ni, α-Ti and Ti₂Ni phases. It was fabricated into filler foil with a thickness of about 45 ?μm by a rapid solidification technique. The results indicate that the liquidus temperature of the Ti–Ni–Nb–Zr brazing alloy was about 978 ^oC, and the brazing alloy presented excellent wettability on TiAl substrate. The TiAl joint mainly consisted of β/B2 phase, Ti₂Al, Ti₂AlNi and α₂-Ti₃Al phases. The diffusion of Al atom from base metal to brazed seam led to the formation of Ti₂Al and Ti₂AlNi. Considering that no previously references on XRD pattern of Ti₂AlNi compound can be found, Ti₂AlNi cast alloy specimen was specially prepared and XRD peaks were specially labeled. The micro-hardness and bending strength tests of the Ti₂AlNi phase were carried out, and the results were 761 HV and 192 ?MPa, respectively. The brazing parameters of 1010 ^oC/10 ?min offered the joint shear strength of 280 ?MPa at room temperature, and the joints exhibited tensile strength of 372 ?MPa at room temperature and 340 ?MPa at 750 ^oC, indicating that the newly developed filler alloy could offer a stable high-temperature strength.     

Thermal stability and magnetic properties of Fe–Co–M–Zr–Nb–Ge–B(M=Mo,Cr) bulk metallic glasses

Fe62Co8 xMxZr6Nb4Ge1B19(M=Mo, Cr) bulk metallic glasses were synthesized in the diameter range up to 2 mm by copper mold casting,which exhibit high thermal stability and large glass-forming ability. The super-cooled liquid region diminishes by the dissolution of Mo. The addition of 2 at% Cr leads to the broading of the liquid region remarkably, resulting in the improvement of thermal stability. The crystallization takes place through a single exothermic reaction, accompanying the precipitation of more than three kinds of crystallized phases such as α-Fe,Fe2Zr and ZrB2. The Fe-based alloys show soft ferromagnetic properties. The saturation magnetization(ss) decreases with increasing Mo or Cr content while the saturated magnetostriction increases with raising Mo or Cr content. There is no evident change in the ssand coercive force(Hc)with annealing temperature below the crystallization temperature, which suggests a more relaxed atomic configuration the glasses have. The crystallization causes a substantial enhancement in both ssand Hc. Each soft magnetic property of the glasses containing Cr with higher thermal stability is superior to that of the alloys containing Mo.     

Effect of Ag addition on the thermal stability and glass-forming ability of Zr<Subscript>35</Subscript>Ti<Subscript>30</Subscript>Cu<Subscript>7.5</Subscript>Be<Subscript>27.5</Subscript> bulk metallic glass

The thermal stability and glass forming ability (GFA) of Zr35-xTi30Cu7.5Be27.5Agx (x = 0-10) alloys were studied by X-ray diffraction (XRD), differential scanning calorimetry (DSC) and ultrasonic techniques. We found that the addition of 1 at.% Ag can considerably enhance the GFA as indicated by an increase in the critical glass dimension from 15 mm in the Zr35Ti30Cu7.5Be27.5 alloy to 20 mm in the Zr34Ti30Cu7.5Be27.5Ag1 alloy. However, with the addition of more Ag the supercooled liquid region (△Tx) and y parameter (defined as Tx/(Tg+Tl)) drastically decreased from 155 K and 0.436 to 76 K and 0.363, respectively, resulting in a decrease in the GFA. Additionally, the elastic constant (the ratio of shear modulus to bulk modulus or Poisson’s ratio) was also used as a gauge to evaluate the GFA in Zr35-xTi30Cu7.5Be27.5Agx alloys.