Purpose: The aim of this work was to fabricate nanocrystalline powders and high-density bulk materials using a sintering method with limited grain growth so as to maintain nanocrystalline structure of the materials also after sintering. Design/methodology/approach: The size of crystallites and physical properties of the obtained nanocrystalline powders and sinters made from these powders were examined. The studied materials were pure copper and the following powders: Cu+1%WC, Cu+3%WC, Cu+3%AlNi and AlNi. The technology for preparation of nano-structured powders was used, which included milling the powders in ball mills and their sintering in a pressing furnace. Findings: It was found that the objective of this work can be achieved provided that high-pressure sintering is used, in which the stages of compacting and sintering proceed simultaneously over a short period of time. Research limitations/implications: It is recommended to perform further studies aimed at checking the possibility of using the proposed method of nanomaterials fabrication in the case of the materials with other chemical composition. Practical implications: This work broadens possibilities of metal powder sintering technology by fabrication of bulk nanocrystalline materials. Originality/value: The results from his work shall be useful in determining conditions for fabrication of nanocrystalline or sub-microcrystalline materials by the sintering method.
Materiał, który poddano badaniom, to austenityczna stal nierdzewna oznaczona według normy EN jako 1.4307. Próbki zostały odkształcone poprzez walcowanie, co dało redukcję 56%, 60% i 62% ich grubości. Badania miały na celu określenie udziału poszczególnych faz w zależności od temperatury, w której poddano próbki odkształceniu, oraz oszacowanie wielkości krystalitów i stwierdzenie naprężeń sieciowych powstałych w stali w wyniku walcowania. Wielkości te oszacowano na podstawie poszerzenia rentgenowskich linii dyfrakcyjnych, zakładając różną postać funkcji aproksymacyjnych.
EN
The material under investigation was a commercial austenitic stainless steel SS 1.4307 (EN) equivalent to AISI 304L. The samples of SS 1.4307 were rolled, achieving a 56, 60 and 62% reduction in thickness. The plastic deformation reduced austenite phase at the expense of the newly formed martensite phase. The volume fraction of austenite phase, crystallite size and lattice strain were calculated from X-ray line broadening. The X-ray diffraction measurements were carried out in a Philips X-Pert diffractometer using KαCu radiation.
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