Snoek-type damping performance in strong and ductile high-entropy alloys

Abstract

Noise and mechanical vibrations not only cause damage to devices, but also present major public health hazards. High-damping alloys that eliminate noise and mechanical vibrations are therefore required. Yet, low operating temperatures and insufficient strength/ductility ratios in currently available high-damping alloys limit their applicability. Using the concept of high-entropy alloy (HEA), we present a class of high-damping materials. The design is based on refractory HEAs, solid-solutions doped with either 2.0 atomic % oxygen or nitrogen, (Ta0.5Nb0.5HfZrTi)98O2 and (Ta0.5Nb0.5HfZrTi)98N2. Via Snoek relaxation and ordered interstitial complexes mediated strain hardening, the damping capacity of these HEAs is as high as 0.030, and the damping peak reaches up to 800 K. The model HEAs also exhibit a high tensile yield strength of ~1400 MPa combined with a large ductility of ~20%. The high-temperature damping properties, together with superb mechanical properties make these HEAs attractive for applications where noise and vibrations must be reduced.

Deformation faulting in a metastable CoCrNiW complex concentrated alloy: A case of negative intrinsic stacking fault energy?

“…Multi-principal-element alloys and the sub-branches of complex concentrated or high-entropy alloys (CCAs or HEAs) have triggered the pursuit of more exceptional mechanical and/or functional performances in the immense central portion of the multi-dimensional phase diagrams [1][2][3][4][5]. Structural alloys developed from this quick-emerging paradigm have already witnessed several salient advantages, such as outstanding strength-ductility synergy at cryogenic temperatures in the facecentered cubic (FCC) systems [6][7][8], and promising yield strength preservation at elevated temperatures in the refractory bodycentered cubic (BCC) systems [9][10][11].…”

Manipulating the ordered oxygen complexes to achieve high strength and ductility in medium-entropy alloys

“…5 . By decomposing the relaxation structure following the method proposed previously, we estimated the proportion of the oxygen atoms which involved in the formation of OOCs in oxygen-doped alloys 16 . A low-temperature peak (red curves) and two high-temperature peaks (yellow and green curves) can be observed in all the oxygen-containing MEAs (see Fig.…”

“…The OOCs not only offer interstitial strengthening of oxygen atoms which significantly increases the strength, but also work as dislocation pinning centers, change the dislocation shear mode from planar slip to wavy slip and significantly enhanced the ductility. Strikingly, OOCs avoid the undesirable embrittlement effects of interstitial atoms and offer an approach to concurrently increasing strength and ductility 15 , 16 . Nevertheless, how to design strong and ductile metallic materials based on the formation of OOCs still remains unclear.…”

Heterogeneity and Memory Effect in the Sluggish Dynamics of Vacancy Defects in Colloidal Disordered Crystals and Their Implications to High‐Entropy Alloys

“…The crystalline structures of our samples, as shown in Figures 1 and 2 (and Supporting Informatio), also show distortions, and the magnitude is comparable to the recent experimental images of HEAs obtained from TEM and STEM. [ 44 , 45 , 46 , 47 , 48 ] Sluggish diffusion means the composite atoms of the HEAs diffuse in the alloy at slower rates compared to the diffusion in their pure element forms. [ 5 , 6 , 7 ] Both the existence and the underlying principles of this core effect are still under hot debate.…”