Abstract
AbstractIn this paper, the microstructure and wear resistance of Zr-17Nb alloy treated by high current pulsed electron beam were studied in detail. A phase change occurs after pulse treatments using X-Ray Diffraction (XRD) analysis, showingβ(Nb) phase andα(Zr) phase transformed by a part ofβ(Zr, Nb) phase. Also, narrowing and shifting ofβ(Zr, Nb) diffraction peaks were found. Scanning Electron Microscope (SEM) and metallographic analysis results reveal that the microstructure of alloy surface before high current pulsed electron beam (HCPEB) treatment is composed of equiaxed crystals. But, after 15 and 30 pulse treatments, crater structures are significantly reduced. Besides, it was also found that the alloy surface has undergone eutectoid transformation after 30 pulse treatments, and the reaction ofβ(Zr, Nb) → αZr +βNb had occurred. Microhardness test results show that microhardness value presents a downward trend as the number of pulses increases, which is mainly due to the coarsening of the grains and the formation of a softerβ(Nb) phase after phase transformation. The wear resistance test results show that the friction coefficient increases first, then decreases and then increases with the increase of pulse number.
Highlights
In this paper, the microstructure and wear resistance of Zr-17Nb alloy treated by high current pulsed electron beam were studied in detail
Scanning Electron Microscope (SEM) and metallographic analysis results reveal that the microstructure of alloy surface before high current pulsed electron beam (HCPEB) treatment is composed of equiaxed crystals
Microhardness test results show that microhardness value presents a downward trend as the number of pulses increases, which is mainly due to the coarsening of the grains and the formation of a softer β (Nb) phase after phase transformation
Summary
Abstract: In this paper, the microstructure and wear resistance of Zr-17Nb alloy treated by high current pulsed electron beam were studied in detail. Zr element can refine the crystal grains, and form a solid solution or a second phase with other alloying elements The presence of these phases can significantly improve the tensile strength and creep resistance of the alloy. A large number of metastable microstructures or phase structures, such as supersaturated solid solutions [17], ultrafine grains [18] and nanostructures [19]. It has widely attracted attention from many researchers [20]. Rapid melting and solidification processes on the material surface are caused in the process of HCPEB treatment, resulting in the formation of ultrafine grain structures. Zou et al [21] studied the martensite transformation of AISI D2 steel by a high current pulsed electron beam, and found that HCPEB can suppress the martensite transformation on the steel surface and achieve austenitizing and nanocrystallization of the material surface, increasing the surface hardness and cor-
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