Phase Separation in Rapid Solidified Ag-rich Ag-Cu-Zr Alloys

The microstructure and phase formation of rapid solidified Ag-rich Ag-Cu-Zr alloys were investigated. Two types of structure; interconnected- and droplet-type structures, were obtained due to phase separation mechanisms. The former was spinodal decomposition and the later was nucleation and growth mechanism. Depending on the alloy compositions, three crystalline phases; FCC-Ag, AgZr and Cu10Zr7 phases were observed along with an in-situ nanocrystalline/amorphous composite. Vickers hardness testing indicated a significant increase of hardness in the nanocrystalline/amorphous-composite alloy

Własności mechaniczne i mikrostruktura złączy zgrzewanych materiałów różnorodnych

The paper presents results of the mechanical testing and the microstructure analysis of dissimilar welded joint of the R350HT steel and the high-manganese (Hadfield) cast steel using Cr-Ni cast steel spacer. The simulation tests of the welded joint surface deformation were carried out. The macroscopic and microscopic investigation were made using light microscopy (LM) and scanning electron microscopy (SEM). Content of the magnetic phase was measured using magnetoscope. The quantitative metallographic investigation was used for assessment of ferrite and martensite contents and X-ray diffraction phase analysis was carried out. The results showed that during cooling of the spacer after welding, the transformation of metastable austenite into martensite proceeded. In addition to work hardening, the phase transformation of austenite into martensite occurs during the process of the superficial deformation of the spacer while simulated exploitation. This leads to a substantial increase of hardness, and at the same time, causes the increase of wear resistance of the welded joints of crossovers.W artykule przedstawiono wyniki badań własności i struktury złącza zgrzewanego stali R350HT ze staliwem wysokomanganowym poprzez przekładkę ze staliwa Cr-Ni. Wykonano symulacyjne procesy odkształcania powierzchni złącza. Przeprowadzono badania makrostrukturalne, mikrostrukturalne LM i SEM, zawartości fazy magnetycznej magnetoskopem, metalograficzną ilościową ocenę martenzytu i ferrytu oraz analizę fazową XRD. Badaniawykazały, że w przekładce podczas chłodzenia po zgrzewaniu występuje przemiana metastabilnego austenitu w martenzyt. Równocześnie w procesie powierzchniowego odkształcania przekładki podczas symulowanej eksploatacji oprócz umocnienia zgniotem zachodzi przemiana austenitu w martenzyt. Prowadzi to do znacznego wzrostu twardości a zatem odporności na zużycie toczne złącza zgrzewanego rozjazdu kolejowego

Mikrostruktura i własności spoin stali półaustenitycznych utwardzanych wydzieleniowo po obróbce cieplnej

This paper presents the studies of the microstructure and properties of the welded joints made of 15-7Mo precipitation hardened semi-austenitic stainless steel welded by Tungsten Inert Gas. Microstructural changes in the heat treated welded joints was assessed. It was found that the joints of 15-7Mo steel in as welded state contain martensite, austenite and δ-ferrite. Scanning electron microscope study of the joints was carried out. The sub-zero and destabilization heat treatment were found to decrease or completely eliminate the austenite in the microstructure and increase hardness of the welded joint.W pracy przedstawiono wyniki badań mikrostruktury i własności złącz spawanych stali nierdzewnej półaustenitycznej utwardzanej wydzieleniowo 15-7Mo wykonanych metodą TIG. Oceniono zmiany mikrostruktury w procesie obróbki cieplnej. Stwierdzono, że w spoinach stali 15-7Mo po spawaniu występuje martenzyt, austenit i ferryt δ. Przeprowadzono badania SEM spoin. Obróbka podzerowa i obróbka destabilizacyjna obniżają lub całkowicie likwidują austenit w strukturze i podwyższają twardość

Cooling Characteristic and Microstructure of Ni-Si-B-Ag Alloy

The aim of this work was to investigate the possibility of obtaining an amorphous/crystalline composite starting from Ni-SiB-based powder grade 1559-40 and silver powder. The alloy was produced using arc melting of 95% wt. Ni-Si-B-based powder (1559-40) and 5% wt. Ag powder. Ingot was re-melted on a copper plate and observed while cooling using a mid-wave infra-red camera. The alloy was then melt-spun in a helium atmosphere. The microstructure of the ingot as well as the melt-spun ribbon was studied using light microscopy and scanning electron microscopy with energy dispersive spectrometry. Phase identification was performed by means of X-ray diffraction. The observations confirmed an amorphous/crystalline microstructure of the ribbon where the predominant constituent of the microstructure was an amorphous phase enriched with Ni, Si, and B, while the minor constituent was an Ag-rich crystalline phase distributed in a film along the melt-spinning direction

Real Time Thermal Imaging of Solid Oxide Fuel Cell

In this work, a mid infrared thermography was used to study thermal behavior of solid oxide fuel cell (SOFC) with a circular shape and a diameter of 90 mm. The emissivity of the anodic surface of the fuel cell was determined to be from 0.95 to 0.46 in the temperature range 550-1200 K and the profile and temperature distribution of the anodic surface of the unloaded cell was given. The surface temperature of the cell was determined during operation and the polarity changes from open circuit voltage (OCV) to 0.0 V. It was found that the cell self-heating effect decreases with increasing temperature of the cell

The effect of γ-phase particles on microstructure and properties of Co-Ni-Ga alloys

The paper concerns the determination of the role of the γ-phase particles on the microstructure and properties of Co-Ni-Ga alloys. The studies cover the alloys of chemical composition which show two types of microstructure: single phase martensite BCT( Body Centred Tetragonal) lattice with c/a > 1(a), BCT + γ(b). The particle analysis was performed to determine the amount of the γ-phase in the studied alloys. The compression test on prism samples proved that the increase of the γ-phase volume fraction significantly improves the strength and plasticity of the alloys. Thus the presence of the γ-phase precipitates cause the decrease of the brittleness observed in the single phase martensitic alloys. TEM observations were performed for specimens before and after deformation to reveal the mechanism of the γ-phase deformation

The microstructure and thermal stability of the two-component melt-spun Ni₅₅Fe₂₀Cu₅P₁₀B₁₀ TCMS amorphous/amorphous composite

The aim of this study is to present the special features and properties of the two alloys of similar average chemical composition Ni₅₅Fe₂₀Cu₅P₁₀B₁₀, processed through two different routes. The first alloy was melt-spun after the ejection of homogeneous liquid using a traditional single chamber crucible, and the second alloy was ejected from a double chamber crucible as two separate liquids: i.e., Ni₄₀Fe₄₀B₂₀ and Ni₇₀Cu₁₀P₂₀, mixing only at the orifice area. The studies of the microstructure of the composite alloy were performed through the use of transmission electron microscopy and scanning electron microscopy. The Ni₅₅Fe₂₀Cu₅P₁₀B₁₀ two-chamber melt-spun (TCMS) alloy, as well as the homogeneous Ni₅₅Fe₂₀Cu₅P₁₀B₁₀, Ni₄₀Fe₄₀B₂₀, and Ni₇₀Cu₁₀P₂₀ alloys, were heated to elevated temperatures and their characteristics studied by means of differential scanning calorimetry. The temperature resistivity change method was applied to the examination of the Ni₅₅Fe₂₀Cu₅P₁₀B₁₀ TCMS alloy. The phase composition after heat treatment was investigated using X-ray diffraction. The results of the microstructure examination show that the TCMS alloy is an amorphous/amorphous composite, and is notable for its Ni-Fe-B and Ni-Cu-P stripes resulting from its differentiated chemical composition. Another unique feature of the TCMS alloy is that it retains its wood-like morphology even after high-temperature heat treatment. The crystallisation of the TCMS alloy starts from the Ni-Cu-P constituent and ends with the Ni-Fe-B areas of the sample. The results are discussed on the basis of previous work completed on amorphous matrix composites

The Microstructure and Thermal Stability of the Two-Component Melt-Spun Ni 55

The aim of this study is to present the special features and properties of the two alloys of similar average chemical composition Ni55Fe20Cu5P10B10, processed through two different routes. The first alloy was melt-spun after the ejection of homogeneous liquid using a traditional single chamber crucible, and the second alloy was ejected from a double chamber crucible as two separate liquids: i.e., Ni40Fe40B20 and Ni70Cu10P20, mixing only at the orifice area. The studies of the microstructure of the composite alloy were performed through the use of transmission electron microscopy and scanning electron microscopy. The Ni55Fe20Cu5P10B10 two-chamber meltspun (TCMS) alloy, as well as the homogeneous Ni55Fe20Cu5P10B10, Ni40Fe40B20, and Ni70Cu10P20 alloys, were heated to elevated temperatures and their characteristics studied by means of differential scanning calorimetry. The temperature resistivity change method was applied to the examination of the Ni55Fe20Cu5P10B10 TCMS alloy. The phase composition after heat treatment was investigated using X-ray diffraction. The results of the microstructure examination show that the TCMS alloy is an amorphous/amorphous composite, and is notable for its Ni–Fe–B and Ni–Cu–P stripes resulting from its differentiated chemical composition. Another unique feature of the TCMS alloy is that it retains its wood-like morphology even after high-temperature heat treatment. The crystallisation of the TCMS alloy starts from the Ni–Cu–P constituent and ends with the Ni–Fe–B areas of the sample. The results are discussed on the basis of previous work completed on amorphous matrix composites