Segregation of Mo atoms into stacking faults in CrFeCoNiMo alloy

Solute segregation at dislocations can impede the motion of dislocations, strengthening materials. Here, we study the formation and role of solute segregation at dislocations in CrFeCoNiMo high-entropy alloys (HEAs) by high-angle annular dark-field scanning transmission electron microscopy imaging and mechanical testing both deformed and annealed samples. Mo atoms exhibit pronounced segregation into the planar-extended core of dislocations, i.e. stacking faults, causing the increase in the yield strength while the loss of the ductility. This work suggests that mechanical properties of HEAs can be tailored by alloying additional elements that are in favor of segregation into dislocations

Strength and plasticity of amorphous silicon oxycarbide

Amorphous SiOC films were synthesized by magnetron sputtering at room temperature with/without radio frequency (RF) bias and further improved in terms of mechanical properties by ion irradiation. As-deposited SiOC films without RF bias exhibit catastrophic failure at a low stress and strain, which is ascribed to microstructural heterogeneities associated with the formation of voids during deposition, as evidenced by transmission electron microscopy. Ion irradiation unifies microstructure accompanied with eliminating the voids, resulting in a simultaneously increase in strength and plasticity (ultimate strength of 5–7 GPa and the strain to shear instability of over 20%). Homogeneous microstructures are demonstrated to ensure high strength and plasticity of amorphous SiOC, as observed in SiOC that are deposited with RF-bias. Thus, microstructural homogeneous amorphous SiOC exhibits intrinsically high strength and plasticity, making them promising as structural engineering materials. Includes supplementary material

Segregation of Mo atoms into stacking faults in CrFeCoNiMo alloy

Solute segregation at dislocations can impede the motion of dislocations, strengthening materials. Here, we study the formation and role of solute segregation at dislocations in CrFeCoNiMo high-entropy alloys (HEAs) by high-angle annular dark-field scanning transmission electron microscopy imaging and mechanical testing both deformed and annealed samples. Mo atoms exhibit pronounced segregation into the planar-extended core of dislocations, i.e. stacking faults, causing the increase in the yield strength while the loss of the ductility. This work suggests that mechanical properties of HEAs can be tailored by alloying additional elements that are in favor of segregation into dislocations

Microstructures and Deformation Mechanisms of FCC-Phase High-Entropy Alloys

Strength and ductility are the most fundamental mechanical properties of structural materials. Most metallurgical mechanisms for enhancing strength often sacrifice ductility, referred to as the strength–ductility trade-off. Over the past few decades, a new family of alloys—high-entropy alloys (HEAs) with multi-principal elements, has appeared great potential to overcome the strength–ductility trade-off. Among various HEAs systems, CrFeCoNi-based HEAs with a face-centered cubic (fcc) structure exhibit a great combination of strength, ductility, and toughness via tailoring microstructures. This chapter summarizes recent works on realizing strength–ductility combinations of fcc CrFeCoNi-based HEAs by incorporating multiple strengthening mechanisms, including solid solution strengthening, dislocation strengthening, grain boundary strengthening, and precipitation strengthening, through compositional and microstructural engineering. The abundant plastic deformation mechanisms of fcc HEAs, including slips associated with Shockley partial dislocation and full dislocations, nanotwinning, martensitic phase transformation, deformation-induced amorphization, and dynamically reversible shear transformation, are reviewed. The design strategies of advanced HEAs are also discussed in this chapter, which provides a helpful guideline to explore the enormous number of HEA compositions and their microstructures to realize exceptional strength–ductility combinations

Influence of Metal Additives on Microstructure and Properties of Amorphous Metal–SiOC Composites

Strong, ductile, and irradiation-tolerant structural materials are in urgent demand for improving the safety and efficiency of advanced nuclear reactors. Amorphous ceramics could be promising candidates for high irradiation tolerance due to thermal stability and lack of crystal defects. However, they are very brittle due to plastic flow instability. Here, we realized enhanced plasticity of amorphous ceramics through compositional and microstructural engineering. Two metal–amorphous ceramic composites, Fe-SiOC and Cu-SiOC, were fabricated by magnetron sputtering. Iron atoms are preferred to form uniformly distributed nano-sized Fe-rich amorphous clusters, while copper atoms grow non-uniformly distributed nano-crystalline Cu particles. The Fe-SiOC composite exhibits high strength and plasticity associated with strain hardening, as well as a good thermal stability and irradiation tolerance. In contrast, the Cu-SiOC composite displays a very low plasticity and poor thermal stability. These findings suggest that the metal constituents play a crucial role in developing microstructure and determining properties of metal– amorphous composites

Strength and plasticity of amorphous silicon oxycarbide

Amorphous SiOC films were synthesized by magnetron sputtering at room temperature with/without radio frequency (RF) bias and further improved in terms of mechanical properties by ion irradiation. As-deposited SiOC films without RF bias exhibit catastrophic failure at a low stress and strain, which is ascribed to microstructural heterogeneities associated with the formation of voids during deposition, as evidenced by transmission electron microscopy. Ion irradiation unifies microstructure accompanied with eliminating the voids, resulting in a simultaneously increase in strength and plasticity (ultimate strength of 5–7 GPa and the strain to shear instability of over 20%). Homogeneous microstructures are demonstrated to ensure high strength and plasticity of amorphous SiOC, as observed in SiOC that are deposited with RF-bias. Thus, microstructural homogeneous amorphous SiOC exhibits intrinsically high strength and plasticity, making them promising as structural engineering materials. Includes supplementary material

Tailoring Mechanical and Electrochemical Properties of the Cr15Fe20Co35Ni20Mo10 High-Entropy Alloy via the Competition between Recrystallization and Precipitation Processes

A strategy to improve the mechanical and electrochemical properties of Cr15Fe20Co35Ni20Mo10 (Mo10) high-entropy alloys (HEA) by regulating the thermal-mechanical process was investigated. Due to the mutual competition between recrystallization and μ-phase precipitation behavior, the microstructure after annealing consists of recrystallized fine face-centered cubic grains with numerous annealing twins, non-recrystallized deformed grains with high-density dislocations as well as high-density nanoscale μ-phase precipitates. The combination of grain boundary strengthening, precipitation strengthening, and hetero-deformation induced strengthening endowed an ultrahigh yield strength of 1189 MPa and a uniform elongation of 17.5%. The increased yield strength activated the formation of stacking faults and deformation twinning as the additional deformation modes, which enabled the Mo10 HEA to exhibit a high strain-hardening rate and thus maintained superior ductility and enhanced tensile strength. Most importantly, when high-density dislocations accumulate at the phase boundaries, the nanoscale μ-phase can plastically deform by dislocation slips and the formation of stacking faults, which can relieve the high stress concentrations and thus prevent the cracking. The electrochemical properties of the annealed Mo10 HEA are decreased (compared to the homogenized ones), but can be optimized by adjusting the content and size and fraction of the μ-phase. This work sheds light on developing high-performance HEAs

Dicarboxylic Amino Acid Permease 7219 Regulates Fruiting Body Type of <i>Auricularia heimuer</i>

Auricularia heimuer is a widely cultivated jelly mushroom. The fruiting bodies are categorized into cluster and chrysanthemum types. With changing consumer demands and the need to reduce bio-waste, the demand for clustered fruiting bodies is increasing. Therefore, gene mining for fruiting body types is a matter of urgency. We determined that the A. heimuer locus for fruiting body type was located at one end of the genetic linkage map. The locus was localized between the markers D23860 and D389 by increasing the density of the genetic linkage map. BlastN alignment showed that the marker SCL-18 was also located between D23860 and D389, and a total of 25 coding genes were annotated within this interval. Through parental transcriptome analysis and qRT-PCR verification, the locus g7219 was identified as the gene controlling the fruiting body type. A single-nucleotide substitution in the TATA box of g7219 was detected between the parents. By PCR amplification of the promoter region of g7219, the TATA-box sequences of the cluster- and chrysanthemum-type strains were found to be CATAAAA and TATAAAA, respectively. This study provides a foundation for the breeding of fruiting body types and strain improvement of A. heimuer