Prealloyed iron-based powders, manufactured in Höganäs Company, are used in the automotive parts industry. The properties and life time of such sintered parts depend, first of all, on their chemical composition, the production method of the prealloyed powder as well as on the technology of their consolidation and sintering. One of simpler and conventional methods aimed at increasing the density in sintered products is the process of activated sintering, performed, for example, by adding boron as elementary boron powder. Under this research project obtained were novel sintered materials, based on prealloyed and diffusion bonded powder, type: Distaloy SA, with the following chemical composition: Fe-1.75% Ni-1.5%Cu-0.5%Mo with carbon (0.55%; 0.75%) and boron (0.2%, 0.4% and 0.6%). Distaloy SA samples alloyed with carbon and boron were manufactured by mixing powders in a Turbula mixer, then compressed using a hydraulic press under a pressure of 600 MPa and sintered in a tube furnace at 1473 K, for a 60 minute time, in the hydrogen atmosphere. After the sintering process, there were performed density and porosity measurements as well as hardness tests and mechanical properties were carried out, too. Eventually, analyzed was the effect of boron upon density, hardness and mechanical properties of novel sintered construction parts made from Distaloy SA powder.Keywords: prealloyed and diffusion bonded powder, carbon, boron, sintering, density, hardness, mechanical properties Proszki stopowane na osnowie żelaza produkowane w firmie Höganäs znajdują zastosowanie w produkcji części motoryzacyjnych. Właściwości i czas eksploatacji tych elementów spiekanych zależą przede wszystkim od składu chemicznego i metody wytwarzania proszku stopowanego oraz od technologii jego zagęszczania, i spiekania. Jednym z prostszych i konwencjonalnych sposobów podwyższania gęstości wyrobów spiekanych jest proces aktywowanego spiekania np. poprzez wprowadzenie dodatku boru w postaci elementarnego proszku boru. W niniejszej pracy badawczej wytworzono nowe materiały spiekane z proszku stopowanego i wyżarzanego dyfuzyjnie typu Distaloy SA o następującym składzie chemicznym: Fe-1,75%Ni-1,5%Cu -0,5%Mo z dodatkiem węgla (0,25% i 0,55% ) i boru (0.2%, 0,4% i 0,6%). Próbki z proszku Distaloy SA z dodatkiem węgla i boru otrzymano metodą mieszania proszków w mieszalniku Turbula, następnie prasowania na prasie hydraulicznej pod ciśnieniem 600 MPa i spiekania w piecu rurowym w temperaturze 1473 K, w czasie 60 min., w atmosferze wodoru. Po procesie spiekania przeprowadzono pomiary gęstości oraz porowatości próbek jak również badania twardości i właściwości mechanicznych. Przeanalizowano wpływ dodatku boru na gęstość, twardość i właściwości mechaniczne nowych elementów konstrukcyjnych z proszku Distaloy SA.

Boron and iron form an equilibrium system exhibiting almost no solubility for three allotropes of iron (a, c, d). If PM Distaloy and Astaloy alloys have many applisintering at a temperature higher than 1433 K, a liquid cations in the automotive industry and are used in phase occurs by eutectic reaction (Liq=ferrite+Fe 2 B). structural elements with different wear resistanceThe solubility of boron in iron is limited, thus, the sintering values. Their main features are adequate density, process runs in the presence of a liquid phase, it contributes hardness, tensile strength, and good ductility. For the to changes in morphology and porosity, and it also purpose of the experiment presented here, Distaloy increases densification and improves mechanical properties. SA and Astaloy Mo powders, alloyed with variousIn order to increase surface mechanical and wear resistance amounts of elemental boron powder, were used. The properties of PM alloys, thermochemical treatments are Distaloy and Astaloy alloys were produced through additionally applied to them. mixing, compacting, and sintering at t=1393 and The nitriding and nitrocarburising routines are consid-1473 K, and, after the completed sintering process, ered the most direct and economic treatments that generate they were plasma nitrided at 793 K. Experimental the absorption of nitrogen or nitrogen and carbon on results showed that if boron was added, while sintersurfaces of treated materials, followed by the bulk diffusion, ing, the shrinkage phenomena increased (1473 K) and along with formation of surface and diffusive layers some parameters of those alloys (density, hardness, containing nitrides or carbonitrides of the Fe-N and and tensile strength) were improved. Upon the ion Fe-C-N systems.10 The treatments contribute to the nitriding treatment of the surface of base Astaloy Mo increase in mechanical, antiwear, and antiseizing properties, samples, a surface layer was created composed of the especially when nitride solution as an intersititial solution, e solution and c∞ nitride, whereas the surface layer on of nitrogen in HCP iron, and c∞, as Fe 4 N, is present. The the Distaloy SA base was mainly composed of a c∞ fatigue endurance properties of the treated elements are compound. Boron activates the sintering process of not influenced by the surface layer composition but the Distaloy SA and Astaloy Mo samples but it has no presence of a diffusion layer favours the increase of fatigue significant impact on the surface layer's thickness of resistance properties of treated pieces.11 While treating Distaloy SA alloys as opposed to Astaloy Mo alloys sintered steels, plasma nitriding and nitrocarburising proin which boron promotes a greater thickness of surcedures have become more and more popular (especially face layers along with a reduced depth of nitrogen for industrial applications) owing to their ecological diffusion.PM/0813 advantages and potential to accurately control surface layer's properties showing negligible dimensional Dr Karwan-Baczewska is at the Univer...

The present work investigates the possibility of using powder metallurgy processing for producing a metal matrix composite. Materials were prepared from AlSi5Cu2 chips with reinforcement of 10, 15, 20 wt. % silicon carbide. Aluminum alloy chips were milled with SiC powder in a high-energy ball mill by 40 hours. Mechanical alloying process lead to obtain an uniform distribution of hard SiC particles in the metallic matrix and refine the grain size. The consolidation of composite powders was performed by vacuum hot pressing at 450 • C, under pressure of 600 MPa by 10 min. The results shows that the addition of SiC particles has a substantial influence on the microstructure and mechanical properties of composite powder as well as consolidated material. Hot pressing is an effective consolidation method which leads to obtain dense AlSi5Cu2/SiC composite with homogeneous structure and advanced mechanical properties.

The paper is focused on the processing of aluminum alloy chips using powder metallurgy. Chips obtained from recycled AlSi5Cu2 alloy were ball milled with the addition of silicon carbide powder with an average size of 2µm. Mechanical alloying process was employed to obtain homogeneous composite powder. The effect of processing time (0 -40h) on the homogeneity of the system was evaluated, as well as a detailed study of the microstructure of AlSi5Cu2 aluminum chips and SiC particles during MA was carried out. Addition of silicon carbide (10, 20wt%) to recycled aluminium chips and application of MA lead to fragmentation of the homogeneous composite powder down to particle size of about 3µm and spheroidization. The addition of hard SiC particles caused reinforcement and reduced the milling time. Higher content of silicon carbide and longer processing time allowed to obtain AlSi5Cu2/SiC powders with microhardness ∼500HV 0.025 . The results of MA were investigated with SEM, EDS, LOM, XRD and showed that relatively homogeneous distribution of SiC reinforcements in the matrix as well as grain refinement of aluminum solid solution down to 50nm can be obtained after 40h of processing.Keywords: AlSiCu alloy chips, Recycling, Powder metallurgy, Mechanical alloying, Al-SiC composite powder W artykule przedstawiono metodę otrzymywania proszku kompozytowego na osnowie wiór stopu aluminium AlSi5Cu2 pochodzących z recyklingu z dodatkiem węglika krzemu (SiC-α, 2µm). Określono wpływ czasu mielenia oraz dodatku SiC na mikrostrukturę i właściwości proszku kompozytowego. Dodatek SiC (10, 20%mas) do wiór stopu aluminium i zastosowanie mechanicznej syntezy pozwala na otrzymanie jednorodnego i drobnoziarnistego proszku o wielkości 3µm i kształcie zbliżonym do sferycznego. Dodatek twardych cząstek SiC powoduje umocnienie proszku oraz skrócenie czasu mielenia. Dodatek SiC i zastosowanie 40h mielenia pozwala otrzymać cząstki proszku o mikrotwardości około 500 HV 0,025 .Badania proszku kompozytowego przeprowadzone na mikroskopie optycznym, SEM oraz TEM potwierdziły jednorodne rozmieszczenie cząstek SiC w osnowie oraz zmniejszenie wielkości ziarna do 50nm po 40 godzinach procesu.

Sintered materials base on pre-alloyed powders (Fe-Ni-Mo-Cu) are expansively applied in the automotive industry. However, their applications are limited by the particular porosity values of those materials. To reduce the porosity and, simultaneously, to increase the consolidation of sintered alloys, miscellaneous methods within powder metallurgy technologies are utilised, as well as an activated sintering process; for example some boron is added. The boron and iron built a system that is not soluble in any of the three allotropic forms of iron. While sintering at a temperature higher than 1433 K, a permanent liquid phase was generated as a result of a eutectic reaction between iron and Fe 2 B. Owing to the limited boron solubility in iron, a liquid phase was continuously present during the sintering process, influence changes in the morphology of the porosity and the increase in density, also mechanical properties. In addition, boron showed a strong chemical affinity to oxygen; in sintering process it reacted with a chemically bound oxygen on the surface of powder particles and it simultaneously activated the sintering process. The paper presents the production of sintered materials based on Höganäs Distaloy SA (Fe-1.75% Ni-0.5% Mo-1.5% Cu) powder modified by boron powder in amounts of 0%, 0.2%, 0.4% and 0.6%. Alloys were manufactured using powder metallurgy technology through mixing of powders, compacting at 600 MPa pressure and sintering at 1473 K, during 30 minutes in hydrogen atmosphere. One of the phenomenon, which exists on the surface of sinters made from boron modified pre-alloyed powders (Fe-Ni-Mo-Cu) type Distaloy SA is creating a thickened layer. The similar thickened layer was observed also on the surface of another samples base on pre-alloyed powders with boron addition.As well as the properties: density, hardness, tensile strength were examined and microstructure investigations were performed. Experimental results showed that if boron was added, while sintering, the shrinkage phenomena increased and properties were improved.Keywords: pre-alloyed powders, boron, activated sintering, thickened layer, properties, microstructure Materiały spiekane na osnowie stopowanego proszku Fe-Ni-Mo-Cu znajdują szerokie zastosowanie w przemyśle motoryzacyjnym. Jednakże ze względu na pewien stopień porowatości tych materiałów ich wykorzystanie jest ograniczone. Ażeby obniżyć porowatość i równocześnie podwyższyć zagęszczenie stopów spiekanych stosuje się różne warianty technologii metalurgii proszków oraz procesy aktywowanego spiekania, na przykład poprzez wprowadzenie dodatku boru. Bor tworzy z żelazem układ o prawie całkowitym braku rozpuszczalności w obu odmianach alotropowych Przy spiekaniu powyżej 1143 K w wyniku reakcji eutektycznej pomiędzy żelazem a Fe 2 B tworzy się faza ciekła. Wskutek ograniczonej rozpuszczalności boru w żelazie proces spiekania przebiega przy ciągłej obecności fazy ciekłej, co w konsekwencji wpływa na zmiany w morfologii porowatości , wzrost zagęszczenia i podwyższenie właściwości mechani...