Erdem Karakulak

Influence of Cu addition on microstructure and hardness of near-eutectic Al-Si-xCu-alloys

The influence of Cu content on the microstructure and hardness of near-eutectic Al-Si-xCu (x = 2%, 3%, 4% and 5%) was investigated. After melting Al-based alloys with different Cu contents, alloys were cast in green sand molds at 690 °C and solidified. The solution treatment was performed at 500 °C for 7 h and then the specimens were cooled by water quenching. The samples were respectively aged at 190 °C for 5, 10 and 15 h to observe the effect of aging time on the hardness of matrix. Also differential thermal analysis was used to obtain the transition temperature of the equilibrium phases at cooling rate of 30 K/min and to determine the effect of Cu content on the formation of quaternary eutectic phases and the melting point of α(Al) + Si. The results show that as Cu content in the alloy increases, the hardness of matrix increases due to precipitation hardening, the melting point of α(Al) + Si decreases and the amount of these eutectic phases increases, quaternary eutectic phase with melting point of 507 °C forms when Cu content is more than 2%.

Effect of Cu content on the corrosion of Al‐Si eutectic alloys in acidic solutions

Purpose – The purpose of this paper is to understand corrosion behavior of different Cu‐containing Al‐Si‐x% Cu alloys (x: 1 wt% Cu, 2 wt% Cu, 3 wt% Cu, 4 wt% Cu, and 5 wt% Cu) in 0.1 M HCl and 0.1 M H2SO4.Design/methodology/approach – Potentiodynamic, chronoamperometric and impedance measurements were applied to specimens to obtain their electrochemical characteristics. For the long‐term analyses, hydrogen evolution with immersion time (V‐t) was measured. The corroded surfaces of the alloys were investigated using scanning electron microscopy (SEM) to understand the corrosion mechanism.Findings – All experimental investigations showed that the corrosion resistance of alloys increased with increasing Cu content in the alloys.Research limitations/implications – Cu‐containing aluminum alloys are age‐hardenable alloys. The corrosion behaviour of these alloys can be changed by heat treatment. Corrosion test results for the heat treated and aged alloys will be discussed in another study.Originality/value – Al‐S...

Microstructural chracterisation of Al-Si-xTi cast alloys

Abstract The present paper reports the existence and morphology of intermetallic particles in Al–Si–xTi cast alloys. Near eutectic Al–Si alloys with 0, 0·1, 1, 2, and 5% Ti have been utilised for this purpose. Metallographic observations were made by the combination of an optical microscope and a scanning electron microscope. Wear tests were performed in a pin on disc tribometer under dry sliding conditions. The addition of Ti to the Al–Si alloys led to the precipitation of TiAlSi intermetallic phase. By increasing Ti content, hardness increases due to increasing volume fraction of relatively hard intermetallics.

Characterisation of nickel alloy powders processed by spark plasma sintering

Abstract In this study, nickel alloy powders were consolidated by spark plasma sintering. Experiments were performed between 700 and 750°C temperature range under 50 MPa pressure with holding times from 5 to 10 min. In addition to these main spark plasma sintering parameters three different heating rates ranging from 100 to 235°C min−1 and two different particle size ranges (75–106 μm narrow size distribution and −45 μm wide size distribution) were used for the experiments. After sintering, the sliding wear behaviour of the samples was investigated. The results revealed that the density of the material increased with raising the sintering temperature and holding time. However, heating rate and particle size also played an important role in the densification and these parameters were investigated in detail.

Effect of heat treatment on erosive wear behaviour of Ti6Al4V alloy

Abstract In this paper, the erosive wear behaviour of Ti6Al4V alloy depending on various heat treatment conditions was evaluated. It is aimed to understand the relationship between the microstructure and the erosion rate of Ti6Al4V alloys. Furthermore, the hardness and the surface morphology variations depending on the annealing parameters and the effects of these parameters on the erosion behaviour of the annealed Ti6Al4V alloy were also considered. Moreover, eroded surfaces of samples were examined by using a scanning electron microscope in order to understand dominant material removal mechanisms depending on the annealing parameters. Results showed that the aging process has dramatically affected the erosion resistance of Ti6Al4V alloy. The microstructure and the hardness of the samples have significantly affected the erosion resistance of the alloy. Surprisingly, erosion resistance decreased when the hardness increased. Finally, SEM investigations of the eroded surfaces of the heat treated samples showed that microcutting and microploughing were the dominant erosion mechanisms occurred during the erosion process.

Effect of nickel on microstructure and wear behaviour of pure aluminium against steel and alumina counterfaces

Abstract In this study, aluminium–nickel alloys with different Ni ratios ranging from 1 to 5 wt-% were produced by casting method. The effect of nickel on the microstructure and hardness properties was studied. The dry sliding wear response of the Al–xNi alloys against steel and alumina counterfaces was investigated. Worn surfaces of the alloys were examined using scanning electron microscopy. The results showed that the hardness of the alloys increases with increasing nickel content. Severe wear damage was observed at low and high nickel contents. Maximum wear resistance was obtained with the addition of 3 wt-% nickel to the pure aluminium under both loads and against both counterfaces.

Effect of heat treatment conditions on microstructure and wear behaviour of Al4Cu2Ni2Mg alloy

Al4Cu2Ni2Mg alloy is an age-hardenable aluminum alloy. The effect of different solution and aging heat treatment conditions on the microstructure, hardness and wear resistance of the alloy was studied. The cast specimens were solution treated and then artificially aged. Optical microscopy and scanning electron microscopy were used to investigate the microstructures of the specimens. The hardness and wear tests were applied to understanding the effects of heat treatment. After aging for 8 h, the hardness of the alloy increases from HV10 96.5 to 151.1. Aging treatment for a longer duration causes a drop in the hardness because of over aging. Increasing the hardness of the alloy increases the wear resistance. As a result of all tests, solution heat treatment at 540 °C for 8 h and aging at 190 °C for 8 h were chosen for optimum heat treatment conditions for this alloy.

Mechanical properties of hypoeutectic Al-Ni alloys with Al3Ni intermetallics

Abstract In this paper, the effect of nickel content on the mechanical properties of aluminum were investigated. High purity Al and Ni were melted in an induction furnace and cast into a metal mold. Microstructural characteristic and mechanical properties of the alloys were studied in detail. The addition of nickel to pure aluminum increased the tensile strength and decreased the elongation at break value of the specimens. Maximum wear resistance was obtained with the addition of 3 wt.-% Ni. Further addition of nickel caused a decrease in wear resistance.

MechanIcal and wear propertIes of pre-alloyed MolybdenuM p/M steels wIth nIckel addItIon

The aim of this study is to understand the effect of nickel addition on mechanical and wear properties of molybdenum and copper alloyed P/M steel. Specimens with three different nickel contents were pressed under 400 MPa and sintered at 1120oC for 30 minutes then rapidly cooled. Microstructures and mechanical properties (bending strength, hardness and wear properties) of the sintered specimens were investigated in detail. Metallographical investigations showed that the microstructures of consolidated specimens consist of tempered martensite, bainite, retained austenite and pores. It is also reported that the amount of pores varies depending on the nickel concentration of the alloys. Hardness of the alloys increases with increasing nickel content. Specimens containing 2% nickel showed minimum pore quantity and maximum wear resistance. The wear mechanism changed from abrasive wear at low nickel content to adhesive wear at higher nickel content.

Effects of Different Heat Treatments on Microstructure, Toughness and Wear Behavior of G-X 10CrNiMoNb 18-10 Cast Austenitic Stainless Steel

In this study, effects of different heat-treatment on microstructure, wear, hardness and toughness behavior of G-X 10CrNiMoNb 18-10 austenitic stainless-steel samples were investigated. The samples were cast in sand mold. Five different cooling conditions were applied in two heat-treatment stages. Microstructures of the as cast and heat-treated alloys were investigated using a scanning electron microscope to understand the effect of cooling rate on the carbide morphology and size. The role of MC and M23C6 carbides on the properties of the alloy was determined. Also, wear tests were carried out to clarify the relationship between different microstructures obtained by different cooling rates and wear properties of the alloy. The toughness of the samples was measured with the Charpy notched-impact test. To understand the heat-treatment effects, microstructural investigations were conducted with scanning electron microscopy. The results of the tests showed that the sample cooled in furnace has superior wear resistance and toughness compared to other samples. The highest wear resistance and toughness value of the furnace cooled sample is a result of finely dispersed carbide particles.