Abstract

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The feasibility of iron-zinc intermetallic-phase preparation by spark-plasma sintering (SPS) was investigated. The samples were prepared with a combination of powder metallurgy, where the powder was prepared in evacuated quartz tubes, and a sintering process using SPS. Since the Fe-Zn intermetallic phases are mostly used for hot-dip galvanized steels, the knowledge of the properties of individual intermetallic phases is vital for a better understanding and even further optimization of galvanization processes. The main aim of the article is to compare the phase composition of the initial powder with the SPS samples using X-ray diffraction. Furthermore, the hardness and microstructure were investigated as well. Keywords: Fe-Zn intermetallics, spark-plasma sintering, diffusion annealing, phase composition, hardness Preu~evana je bila izvedljivost priprave`elezo-cink intermetalnih faz s sintranjem v iskre~i plazmi (SPS). Vzorci so bili pripravljeni s pomo~jo metalurgije prahov, kjer so bili prahovi zaprti v evakuirane kvar~ne cevi, ki mu je sledil postopek SPS. Ker se Fe-Zn intermetalne faze ve~inoma uporablja pri vro~em cinkanju jekel, so lastnosti posamezne faze pomembne za bolj{e razumevanje in celo za optimiranje procesa galvanizacije. Glavni namen~lanka je primerjava sestave faz s pomo~jo rentgenske difrakcije v za~etnih prahovih in SPS vzorcih. Preiskovani sta bili tudi trdota in mikrostruktura. Klju~ne besede: Fe-Zn intermetalne zlitine, sintranje z iskre~o plazmo, difuzijsko`arjenje, sestava faz, trdota

The aim of this study was to prepare an aluminium alloy with high temperature stability using the powder metallurgical route. Gas atomized powder of the Al-Zr-Ti alloy was consolidated by the spark plasma sintering (SPS) technology. The fine grained structure (grain size between 2 and 3 µm) observed in the gas atomized powder was retained after sintering both at 425 • C and 550 • C. The microhardness of 49 HV observed in the gas atomized powder was increased up to about 100 HV in the SPS compacts. Precipitation of the Al3(Zr,Ti) phase during sintering can explain this strengthening. The materials stability was tested by annealing at temperatures above 450 • C. The grain size remained stable even after 10 h of annealing. A decrease in microhardness by about 20% can be attributed especially to the formation of the stable modification of the Al3(Zr,Ti) phase.

Quality of electrically conductive adhesives is a main component in electronic packaging. It highly influences the total quality of a product containing such a component. With time and usage, adhesives lose some of the qualities. In some cases, changes in the molecule structure for example, can be responsible for this influence on material characteristics. This process is known as aging. It can badly affect the total electrical conductivity of adhesives and non-linearity, even mechanical properties of adhesive joints can be affected. In research field, aging is applied to test the expected reactions of the most important material parameters of electrically conductive adhesives. It also helps identifying the total operating life of the tested components. This work focuses primarily on analyzing the effect of thermal aging on the resistance of three types of adhesives, one of these adhesives is a two-component type, and the other two are onecomponent type.