Age-hardening of Ti-35Nb-7Zr-5Ta alloy for orthopaedic implants Taddei, Elisa Bueno; Henriques, Vinicius Andre Rodrigues; Silva, Roberto Moreira da ...
Materials research (São Carlos, São Paulo, Brazil),
09/2007, Letnik:
10, Številka:
3
Journal Article
Recenzirano
Odprti dostop
Bone injuries and failures often require the inception of implant biomaterial. Research in this field has received increasing attention recently. In particular, porous metals are attractive due to ...its unique physical, mechanical, and new bone tissue ingrowth properties. The aim of this work is to investigate age hardening behavior of Ti-35Nb-7Zr-5Ta alloy produced by powder metallurgy. Samples of Ti-35Nb-7Zr-5Ta were produced from a mixture of hydrided powders followed by uniaxial and cold isostatic pressing with subsequent densification by sintering at 1500 °C, in vacuum. After that, the samples were heat treated in three steps; solution treatment (1100/°C), air cooling and aging (600 °C for 4 and 6 hours). Sintered samples were characterized for microstructure and microhardness by scanning electron microscopy and Vickers indentation, respectively. In the homogenized condition alloy exhibited a microstructure consisting primarily of a beta Ti matrix with grain boundary alpha precipitates and a low volume fraction of primary alpha precipitates. In the ageing condition the alloy exhibited the precipitation of refined scale secondary alpha precipitates distributed homogeneously in the beta matrix.
This work studies the influence of time of treatment in the formation of nitride layer of AISI D2 tool steel and the resistance to micro-abrasive wear from the technique of nitriding in plasma. The ...samples were nitrides at 400 degree C with a pressure of 4.5 mbar (450 Pa) and using a gas mixture of 80% vol.H2 and 20% vol.N2. The times of treatment were: 30, 60, 120, 180 and 360 minutes. The properties of the layers in the samples obtained nitrides were assessed by surface microhardness, profiles of microhardness, metallography analysis, X-ray diffraction and test for resistance to micro-abrasive wear. The best results for nitriding to 400 degree C, was obtained with the time of treatment of 360 minutes. In this case the increase in surface hardness was 94.6% and resistance to micro-abrasive wear of 15%. This increase in hardness may be associated with high concentration of nitrogen in the crystalline network of iron- and additional training of nitrides. Low temperature of nitriding reduces between grain fragility to reduce the likelihood of precipitation of nitrides in a continuous manner in the austenite grain boundaries and the absence of previous epsilon ' + gamma phases.
Mechanical properties of Sialon da Silva, Cosme Roberto Moreira; de Melo, Francisco Cristova˜o Lourenço; de Macedo Silva, Olive´rio Moreira
Materials science & engineering. A, Structural materials : properties, microstructure and processing,
05/1996, Letnik:
209, Številka:
1
Journal Article, Conference Proceeding
Recenzirano
Silicon nitride based ceramics have several important applications in the fabrication of hard materials, such as ceramic cutting tools. In this work, aluminum nitride, yttrium oxide and cerium oxide ...were used as sintering aids on pressureless sintered Si
3N
4. The relationships between the type and quantities of these additives with micro hardness (HV), fracture toughness and formed crystalline phases, such as Sialon, have been evaluated. The correlation between microstructure and the mechanical properties has been studied, using the scanning electron microscopy.
The Cystic Mesothelioma: case report Melo Teixeira Batista, Hermes; Cosme da Silva, Jéssica; Bezerra Rulim, Marco Antônio ...
International archives of medicine,
2015
Journal Article
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