In this study, boro-titanizing treatment was applied to AISI 1040 steel. In the coating treatment, steel samples were pre-boronized in a slurry salt bath consisting of borax, boric acid and ferro-silicon at 900• C for 2 h, then titanized by thermo-reactive deposition technique (TRD) in a powder mixture consisting of ferro-titanium, ammonium chloride, alumina and naphthalene at 1000• C for 14 h. The coated samples were characterized by Xray diraction analysis (XRD), scanning electron microscope (SEM), glow discharge optical emission spectroscopy (GDOES) and micro-hardness tests. Coated layer formed on the pre-boronized AISI 1040 steel was compact and homogeneous. X-ray studies showed that the phases formed on the steel surfaces are TiB2, TiC, TiN and Fe2B. The depth of the coating layer ranged from 3.41 ± 0.47 µm to 6.59 ± 0.51 µm, depending on treatment time. A higher treatment time resulted in a thicker boro-titanized layer. The average hardness of the coating layer was 4527 ± 284 HV0.005.

In the present study, the production of Fe-Ti-B based alloys was realized and their structure and properties were investigated. Mechanical alloying proceeds by the continual cold welding and fracturing of the constituent mixture of Ti+4B+5Fe powder when subjected to the large compressive forces of a high speed mill. The powder charge together with 7 mm diameter steel balls were loaded into a tool steel grinding container at approximately 350 RPM for 20 h. The samples were shaped as cylinder of Ø15×8 mm dimensions by uniaxial pressing at 450 MPa. Then, the green body materials were produced by sintering at 1100• C for 14 h in argon atmosphere. The morphology of composite materials was investigated by optical microscopy and scanning electron microscopy and phase analysis was realized by x-ray diraction analysis. The bulk densities of the materials were measured using by Archimedes method. Also, the micro-hardness of the samples was measured by Vickers indentation technique. As a result, Fe, iron boride (FeB, Fe2B) and titanium boride (TiB2) phases were detected in the phase analysis of the Fe-Ti-B based materials. The hardness of the materials was measured between 1107 HV0.05 and 1551 HV0.05, depending on sintering time. The densities of the samples were determined between 4.205 g/cm 3 and 4.219 g/cm 3 .

Abstract. In this paper, we investigated the possibility of deposition of niobium boride layers on the surface of AISI D2 steel by a duplex treatment. At the first step of duplex treatment, boronizing was performed on AISI D2 steel samples at 1000 o C for 2h and then pre-boronized samples niobized at 850°C, 900°C and 950 o C using thermo-reactive deposition method for 1-4 h. The presence of the niobium boride layers such as NbB, NbB 2 and Nb 3 B 4 and also iron boride phases such as FeB, Fe 2 B were examined by X-ray diffraction analysis. Scanning electron microscope (SEM) and micro-hardness measurements were realized. Experimental studies showed that the depth of the coating layers increased with increasing temperature and times and also ranged from 0.42 μm to 2.43 μm, depending on treatment time and temperature. The hardness of the niobium boride layer was 2620±180 HV 0.005 .