This study demonstrates that homogeneous high-purity micropowders with grain size of 10–45 µm from refractory NiAl-Cr(Co)-Hf alloy can be produced by combustion elemental synthesis and further treated in a thermal plasma flow. The optimal parameters of plasma spheroidization of the synthesized powders are shown at which the resulting spherical alloy particles are characterized by high sphericity (~ 98%) and the absence of satellites or internal porosity. The spherical powders were consolidated by HIP. The alloy structure was investigated by scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). The fine structure and features of segregation of hardening nanoparticles of Ni₂AlHf (the Heusler phase) and hafnium solid solution (ssHf) in the NiAl matrix were thoroughly studied. Furthermore, in situ examination of structural phase transformations occurring in the as-HIP NiAl-based alloy was carried out upon heating in the temperature range of 25–850 °C. The α-Cr phase nanoparticles are formed inside the NiAl grains via two different mechanisms: (1) spinodal decomposition of solid solution at 250–450 °C resulting in segregation of the Guinier-Preston zone rich in Cr and its subsequent transformation into α-Cr precipitates 25–170 nm in size; (2) heterogeneous nucleation and growth of α-Cr nanocrystallites 7–40 nm long on prismatic dislocation loops at 750–850 °C.

The thermomechanical properties of the alloy were studied in the temperature range of 596–1100 °C on a Gleeble System 3800 testing system. The correlation between the thermal load and the high-temperature creep rate, as well as the temperature dependences of the Young's modulus (E), the offset yield strength (σ_0.2), and the rate sensitivity coefficient (m), were ascertained. The Young's modulus (E), the ultimate tensile strength, the offset yield strength σ_0.2, and the proportional limit of the alloy being examined during uniaxial compression test of a cylindrical sample at 750 °C and at true strain rate of ~ 0.01 s⁻¹ were as high as 137.8 GPa, 682, 455 and 358 MPa, respectively.

这项研究表明，难熔的NiAl-Cr（Co）-Hf合金可制得晶粒尺寸为10-45 µm的均质高纯度微粉，可以通过燃烧元素合成法制备，并在热等离子体流中进一步处理。示出了合成粉末的等离子体球化的最佳参数，在该参数下，所得球形合金颗粒的特征在于高球形度（〜98％）并且不存在人造卫星或内部孔隙。球形粉末通过HIP固结。通过扫描电子显微镜（SEM）和高分辨率透射电子显微镜（HRTEM）研究了合金结构。Ni ₂硬化纳米颗粒的细化结构和偏析特征彻底研究了AlHf（Heusler相）和NiAl基体中的solid固溶体（ssHf）。此外，在25–850°C的温度范围内加热时，对as-HIP NiAl基合金中发生的结构相变进行了原位检查。α-Cr相纳米颗粒是通过两种不同的机制在NiAl晶粒内部形成的：（1）在250–450°C时旋溶分​​解固溶体，导致富含Cr的Guinier-Preston区偏析并随后转变为α- Cr沉淀在25-170 nm的范围内。（2）在750-850°C的棱柱形位错环上长7-40 nm的α-Cr纳米微晶的异质成核和生长。

在Gleeble System 3800测试系统上，在596–1100°C的温度范围内研究了合金的热机械性能。热负荷和高温蠕变速率之间的杨氏模量的温度依赖性（E）的相互关系，以及，偏移屈服强度（σ _0.2和速率灵敏度系数（M）），分别确定。杨氏模量（E），极限拉伸强度，偏移屈服强度σ _0.2，在750℃，并在〜0.01秒的真实应变率的圆柱形试样的单轴压缩试验过程中被检查，并且该合金的比例极限^{- 1}分别高达137.8 GPa，682、455和358 MPa。