Papers by Keyword: Elemental Powders

Abstract: This paper presents the results of the study of Selective Laser Melting (SLM) process for the in-situ synthesis of Ti-6Al-4V alloy from elemental powder mixture. Elemental spherical powders of Ti, Al and V were used to prepare a powder mixture, and then bulk specimens were produced by SLM using different process parameters. The effects of SLM process parameters on samples’ relative density, their chemical composition, the formed microstructure and microhardness before and after heat treatment have been studied. It was shown that volume energy density during the SLM process significantly effects the microstructure and microhardness of Ti-6Al-4V obtained from elemental powders. The difference in microstructure morphology and microhardness remains after heat treatment.

Abstract: This work investigates the Selective Laser Melting (SLM) process for the in-situ synthesis of Ti-5Al and Ti-6Al-4V alloys using elemental powder mixture. Elemental spherical powders were used to prepare a powder mixture and then samples were produced by SLM using different volume energy density. The effects of volume energy density during SLM on samples’ relative density, chemical composition, microstructure and microhardness before and after heat treatment have been studied. It was shown that volume energy density during the SLM process significantly effects the density, microstructure of Ti-5Al and Ti-6Al-4V alloys, as well as, the microhardness of Ti-6Al-4V obtained from elemental powders.

Abstract: As a new effort, combined reactive sintering with hot pressing technique, the Ti-22Al-25Nb alloy was successful prepared with element mixed powders. Meanwhile, the reactive sintering was divided into two temperature ranges, which were at 873 K and 1373 K, respectively. The starting sintering kept 1h at 873K, and then the temperature was increased to 1373K, keeping 2h. The orthorhombic (Ti2AlNb) phase was observed in this sintered alloy. Moreover, the homogenization treat was conducted at 1473 K for 2h after the final sintering was accomplished, and the fraction of the orthorhombic phase increased significantly. The microstructures and the phases were analyzed. And the generation mechanism of the orthorhombic phase was also analyzed.

Abstract: Ti/Al(Ti-50at.%Al) composite powders were prepared by high-energy ball milling followed by reaction sintering heat treatment at 550°C ~ 650°C for 2 hours. Mechanical alloying of TiAl had been performed in a high energy plant ball after different milling times and pre-sintered at different temperatures. The particle sizes of Ti/Al powders were analyzed by scanning electron microscopy (SEM). X-ray diffraction (XRD) analysis was performed for microstructural characterization. The results show that microstructural and morphological changes of high energy milled powder are studied as a function of milling time. Over 600°C TiAl powders are completely alloyed by being sintered at different temperatures. The powders are mainly composed of γ-TiAl as well as a small amount of AlTi3. The TiAl alloy powders of high energy ball mill/2h and sintered at 650°C/2h get plasma spheroidization. Spheroidizing powders with fine texture, γ-TiAl and AlTi₃ phase, particle size of 10~40μm are obtained.