M. Perek-Nowak

Ag Powders Consolidated by Reciprocating Extrusion (CEC)

CEC has unique characteristic. These are applicability of very large strain and deformation under high hydrostatic pressure. Due to these abilities of CEC, several unique phenomena have been observed. One of them is the possibility of consolidation of metallic powders in room temperature to the form of bulk material. In the present paper the consolidation of AgSnBi and AgNi to bulk composites was presented. Applying the deformation of  = 0.42 in the single cycle of CEC, under high hydrostatic pressure, the samples without pores and discontinuities were fabricated. The microstructure observations were performed by optical microscopy (MO), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). They show refinement of microstructure at all levels of observation. The nanometric-size subgrains/grains were found inside consolidated granules. The microhardness level of AgSnBi in average achieved level 110 μHV100, and AgNi of about 90 μHV100. The AgSnBi samples consolidated by CEC and additional hydrostatically extruded to wires with 3 mm in diameter average showed 500 MPa yield point.

Analysis of Eneolithic Copper Jewellery Artifacts from Książnice Cemetery in South Poland

This paper presents a metallographic analysis of copper artifacts from an extraordinary Polish cemetery of Lublin–Volhynian culture dated 4000–3800 BC (Wilk in Analecta Archaeologica Ressoviensia, 2014, pp. 209–243). The Książnice necropolis, Busko-Zdrój county located in South Poland, is characterized by an unprecedented collection of prestigious objects made of copper, rare in the Eneolithic period in Poland. The archaeological studies supplemented with materials analyses give knowledge of prehistoric metallurgy and the processing of copper. For the described group of artifacts, non-destructive microscopic studies were performed including chemical analysis by means of X-ray fluorescence and energy-dispersive X-ray spectroscopy using a scanning electron microscope. The mentioned studies allowed for raw material characteristics of this important discovery.

Metallographic Studies of Selected Eneolithic and Bronze Age Artifacts from Poland

This work presents the results of metallographic studies performed on four Eneolithic and Bronze Age artifacts from Poland. All of them are of none archaeological context therefore its academic value is strongly reduced. The aim of this work is to deal with such a reduced data in a way of improving and verifing current state of knowledge about the artifacts. In order to achieve this goal elemental composition (XRF), microstructure analysis (SEM-EDS), macrostructure analysis (optical microscopy) and 3D scanning were performed.

Influence of Al and Fe Additions on Structure and Properties of Cu-Sn Alloys

The studies regard analysis of variable Al and Fe additions on the chosen group of CuSn alloys. The group of tin bronzes known and applied for thousands of years has still found its application in many branches of industry, however it was observed that small amounts of aluminum and iron may affect the original properties strongly. The changes of mechanical properties and microstructure is discussed in detail. Aside of many advantageous properties of these bronzes, it is noted that the mentioned alloying additions have beneficial effect on the gas-induced shrinkage porosity. Simultaneously, the effect of the aluminum addition on the characteristic phase transformation points was determined basing on the analysis of calorimetric curves. The results are correlated with microstructure observations.

Influence of Molybdenum and Boron Addition on Fracture of P/M Parts

Samples made of iron powder with addition of 1.5 and 2% of molybdenum and 0-0.6% of boron were compacted at 600 MPa and sintered at 1200°C for 60 minutes in hydrogen atmosphere after mixing in Turbula mixer. The samples were deformed in a tensile test till rupture. The effect of molybdenum and boron on topography of fracture is discussed. It is noted that the sintering mechanism changes upon addition of boron particles into Fe-Mo alloy. The fractures of the studied samples were observed by means of scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The addition of Mo influences the change of fracture to ductile type. The type of fracture is brittle with Mo and borides segregating to grain boundaries. In the alloys with low concentrations of molybdenum boron induces brittle transgranular fracture.

Microstructure of AgNi and AgSnBi Powders Consolidated by CEC

Powder metallurgy is widely used to the production of AgNi and AgSnBi powders employed for electrical contacts. In the work AgNi and AgSnBi powders were consolidated by the cyclic extrusion compression (CEC) method enabling cyclic unlimited deformation. In the initial stage the AgNi powder contained the two phases Ag and Ni, recognized by the EDX technique using scanning electron microscopy (SEM). The investigations shown that the Ni phase is distributed in the form of small granules around larger Ag granules. In the AgSnBi powder phases Ag + Bi + Ag3Sn (ξ) were distributed uniformly. It was found that after the CEC consolidation phases were excellently joined without cavities and cracks. Detailed observations of microstructure have been performed by the transmission electron microscopy (TEM) and revealed inside the consolidated granules nanometric grains with the nanometric twins inside.