Abstract

A comprehensive comparative study of the structure, phase composition, and mechanical properties of heat-resistant nickel-based Ni–Cr–(X) alloys produced by the methods of traditional metallurgy and self-propagating high-temperature synthesis (SHS metallurgy) is carried out. With the purpose of formation of the submicrocrystalline structure, a longitudinal rolling and post-deformation annealing of the cast alloy is performed. The microstructure of the heat-resistant alloys is investigated by the SEM and TEM methods. It is shown that the cast alloy has a recrystallized structure with the mean grain size of ~1 μm and the particles of chromium carbides have a size of ~1–3 μm. After rolling and subsequent annealing (750°C/1 h), the average grain size is reduced to 0.43 μm and the formation of dispersed particles of carbides 100 nm in size is observed. The structure of the alloy obtained by SHS metallurgy is dendritic, and particles of W and Cr are absent. When 0.1 wt % carbon powder is added to the initial powder mixture for SHS synthesis, formation of the network of W and Cr particles is observed along the boundaries of dendrite colonies. It is found that the SHS Ni-based heat-resistant alloy similar in composition to commercial cast alloy is characterized by improved mechanical properties and increased heat resistance compared to the cast alloy in both the coarse-grained and the submicrocrystalline state. Adding the carbon powder to the powder mixture for SHS leads to a further increase in the resistance to high-temperature deformation owing to formation of the carbide phase impeding the movement of dislocations and grain boundary creeping processes.

中文翻译：

---

不同方法制备的镍基高温合金的结构，相组成和力学性能的比较研究

摘要

对通过传统冶金和自蔓延高温合成（SHS冶金）方法生产的耐热镍基Ni–Cr–（X）合金的结构，相组成和力学性能进行了全面的比较研究。出来。为了形成亚微晶结构，进行铸造合金的纵向轧制和变形后退火。通过SEM和TEM方法研究了耐热合金的显微组织。结果表明，铸造合金具有重结晶组织，平均晶粒尺寸约为〜1μm，碳化铬颗粒的尺寸约为〜1-3μm。轧制并随后退火（750°C / 1 h）后，平均晶粒尺寸减小至0.43μm，并且观察到形成了尺寸为100 nm的碳化物分散颗粒。通过SHS冶金获得的合金的结构是树枝状的，并且没有W和Cr的颗粒。当将0.1重量％的碳粉添加到用于SHS合成的初始粉末混合物中时，沿着枝晶菌落的边界观察到W和Cr粒子的网络的形成。发现与在粗粒状态和亚微晶状态下的铸造合金相比，在组成上与市售铸造合金相似的SHS Ni基耐热合金的特征在于改善的机械性能和增加的耐热性。将碳粉添加到用于SHS的粉末混合物中，由于碳化物相的形成阻碍了位错的运动和晶界蠕变过程，导致对高温变形的抵抗力进一步提高。