Fe₇₁Si₁₆B₉Cu₁Nb₃ amorphous alloy ribbons were prepared with a single roll polar method. X-ray diffraction analysis of the surface samples was completely amorphous. The thermal stability parameters T _x, T _p, and T _end of amorphous ribbons were measured with a synchronous thermal analyzer under high purity argon gas and analyzed for their crystallization behavior. The heating rate was 10 K min⁻¹, 15 K min⁻¹, 20 K min⁻¹, and 30 K min⁻¹. The T _x and T _p of the Fe₇₁Si₁₆B₉Cu₁Nb₃ amorphous alloy increased with an increase in the heating rate, indicating that the crystallization behavior has a kinetic effect. The crystallization activation energy of the amorphous alloy was calculated using the Kissinger and Ozawa equations, respectively. The calculation results of the two methods were consistent. The sample was annealed (761 K, 786 K, 801 K, and 858 K, holding for 300 s) under the protection of high purity argon. The phase transition and microstructure transformation of the amorphous alloy during isothermal crystallization were analyzed by x-ray diffraction. When the alloy was annealed at 801 K, a single α-Fe(Si) solid solution precipitated on the amorphous matrix. Magnetic properties were measured using a vibrating sample magnetometer and observed by transmission electron microscopy. When the alloy was annealed at 786 K and 801 K, the saturation magnetic induction reached 1.22∼1.27 T, coercivity was as low as 5.3∼7.2 A m⁻¹, and the average grain size was about 10∼20 nm.

A WC-particle-reinforced nickel-based alloy surfacing layer was fabricated on 42CrMo ultra-high-strength steel. The microstructure and the mechanical and impact-damage behaviors of the surfacing layers at the evaluated temperatures were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and the Vickers hardness tester. Results showed that these WC particles gradually changed from elongated and crisscross needle-like phases to blocks with the increase in impact temperature. Numerous carbide phases (e.g., (Cr,Ni,Fe)₂₃C₆) and γ-Ni phases were formed in the substrate matrix. The surfacing layer showed a typical brittle fracture, and the impact energy decreased with the increase in temperature. Moreover, the surfacing layer showed a clear quasi-cleavage fracture morphology without dimples after a 600 °C impact test but exhibited a mixture of dimple fractures and cleavage fractures after the 200 °C and 400 °C impact tests. The Vickers fracture toughness test showed that the average hardness of the surfacing layer after a 600 °C impact test was 383 HV_1.0, which is about 0.8 times that after the 200 °C impact test. In addition, the WC particles in the surfacing layer after the 600 °C impact test showed the highest fracture toughness, but the corresponding Ni40A binder phase possessed the lowest fracture toughness.

In this paper, rare earth element yttrium (Y) was selected to be doped into AlCoCrFeNi_2.1Y _{x (x = 0, 0.1%, 0.3%, 0.5%, and 1.0%)} high-entropy alloy in order to refine grain and increase yielding strength. The precipitation behavior of the Y-rich nano-phases in the face centered cubic (FCC (L1₂)) phase and the body centered cubic (BCC (B2)) phase was investigated by x-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy and differential scanning calorimetry. Refined crystal grains were observed due to the high-density precipitation. The nano-phase within the BCC(B2) phase was (Al-Ni-Y)-rich phase and single cubic (SC) structure. The nano-phase formed within the FCC (L1₂) phase was (Fe-Co-Cr-Y)-rich phase and FCC structure. Fine (Al-Ni-Y)-rich nano-particles were formed due to the addition of Y and the amount of the nano-phase increased with increasing Y content. The adoption of Y promoted dispersed precipitation of (Al-Ni-Y)-rich nano-phase under deformation. The more Y content, the more nano-precipitates. When Y =1.0 at.%, the lamellar structure was transformed into bamboo-like structure in the BCC phase due to the segregation of Y. Double yielding phenomenon occurred during the compression deformation of the AlCoCrFeNi_2.1Y _x alloys (when x ≥ 0.5 at.%) and caused an increase of yielding strength by 40%. It was since the barrier effect of both the (Al-Ni-Y)-rich nano-precipitation and the (Fe-Co-Cr-Y)-rich nano-phases on the dislocations within grains and grain boundaries led to the second yielding. With the further increase of Y content, the lamellar BCC phase was separated from the bamboo-like BCC phase owing to the super-saturated precipitation and segregation of Y at the solidification front of B2 phase, leading to a degradation of mechanical properties.