http://hdl.handle.net/10204/919 2013-05-25T14:31:36Z http://hdl.handle.net/10204/6708 Title: Effects of Ti and TiC ceramic powder on laser-cladded Ti-6Al-4V in situ intermetallic composite Authors: Ochonogora, OF; Meacock, C; Abdulwahaba, M; Pityana, S; Popoolaa, API Abstract: Titanium metal matrix composite (MMCs) was developed on titanium alloy (Ti–6Al–4V) substrate with the aim of improving the hardness and wear properties by laser cladding technique using a Rofin Sinar 4 kW Nd: YAG laser. Wear investigations were carried out with the aid of three body abrasion tester. The resultant microstructure show homogeneous distribution of TiC particles free from cracks and pores. Multiple track deposited systems with 50% overlap revealed micro-hardness increase from 357.3 HV0.1for the substrate reaching a peak as high as 922.2 HV0.1 for 60%Ti + 40%TiC and the least 665.3 HV0.1 for 80%Ti + 20%TiC MMCs. The wear resistance of the materials improved significantly, indicating a fifteen-fold wear rate reduction due to the proper distribution of ceramic particles thereby forming interstitial carbides as revealed by the X-ray diffraction spectrum. Description: Copyright: 2012 Elsevier. This is an ABSTRACT ONLY. The definitive version is published in Applied Surface Science, vol. 263, pp 591-596 2012-12-01T00:00:00Z http://hdl.handle.net/10204/6652 Title: Phase characterisation in spark plasma sintered TiPt alloy Authors: Chikosha, S; Mahlatji, ML; Chikwanda, HK Abstract: The conclusions drawn from this presentation are that Spark Plasma Sintering (SPS) of equiatomic BE TiPt powder produces fully sintered specimens, with incomplete homogenisation. There is a need for improved furnace atmosphere control so that contamination can be eliminated as a possible reason for deviation of the final microstructure from the expected equiatomic TiPt composition. Description: The presentation was presented at the 49th Annual Conference of the Microscopy Society of Southern Africa (MSSA 2011), hosted by the Nanoscience Centre of the CSIR at the CSIR International Convention Center, Pretoria, South Africa, 4-9 December 2011. 2011-12-01T00:00:00Z http://hdl.handle.net/10204/6632 Title: DSC study of martensite transformation in TiPt alloys Authors: Chikosha, S; Mahlatji, ML; Chikwanda, HK Abstract: Conclusions drawn from this presentation were that when SPS, HP and Press and Sinter methods were used to form TiPt phase from elemental Ti and Pt powders, Press and Sinter was less successful. Presence of Ti-rich and Pt-rich phases coexisting with TiPt phase after SPS and HP shows incomplete homogenisation, the volume fraction of TiPt phase formed by various solid-state diffusion methods ranges from 40-55%. DSC shows two-stage B2-B19 martensite transformation, an intermediate phase of unknown structure, forms during the phase transition. Description: CSIR, Materials Science and Manufacturing. Munich, Germany, 11-13 September 2012 2012-09-01T00:00:00Z http://hdl.handle.net/10204/6629 Title: Semi-solid high pressure die casting of metal matrix composites produced by liquid state processing Authors: Ivanchev, L; Camagu, ST; Govender, G Abstract: There are two main technologies for manufacturing of particulate reinforced metal matrix composites (MMC), solid state and liquid state processing. The great challenge of producing cast metal matrix composites is to prevent agglomeration of particulates. This tendency is more pronounced with decreasing the particulate size to fine micro- and nano size. A method for producing MMC was successfully implemented for mixing hybrid, nano and low micron sized, reinforcing particles in an aluminium alloy matrix. The hybrid SiC particles were produced by milling 3µm to 5µm SiC particles to a particle size range between 2.5µm and 150 nm. The hybrid particles were mixed with A356 aluminium alloy under combined magneto-hydrodynamic (MHD) and mechanical stirring. The composite was then transferred to a High Pressure Die Casting (HPDC) machine in the semi-solid state. The micron size particles were found to be predominantly in the intergranular eutectic while the nano-particles were predominantly in the primary a-Al grains. Increased ultimate tensile strength, yield strength and hardness were achieved for the new cast metal matrix hybrid component (MMHC) alloy. Description: Copyright: 2012 Trans Tech Publications. This is an ABSTRACT ONLY. The definitive version is published in Solid State Phenomena, vol. 192-193, pp 61-65 2012-10-01T00:00:00Z