Banca de DEFESA: PÂMALA SAMARA VIEIRA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : PÂMALA SAMARA VIEIRA
DATE: 30/12/2024
TIME: 09:30
LOCAL: Plataforma de Google meet
TITLE:

Microstructure and Properties of the WC-10%CrMnFeCoNi Composite via High-Energy Milling

KEY WORDS:

High-entropy alloys; CrMnFeCoNi; Powder metallurgy; High-energy ball milling; Spark plasma sintering

PAGES: 78
BIG AREA: Engenharias
AREA: Engenharia de Materiais e Metalúrgica
SUBÁREA: Metalurgia de Transformação
SPECIALTY: Metalurgia de Pó
SUMMARY:

The vast majority of metal alloys have one main matrix, with additions of secondary elements to improve their properties. However, high entropy alloys (HAE) challenge this paradigm by using multiple main elements, creating a simple solid solution, which results in excellent characteristics and properties. The CrMnFeCoNi alloy, considered one of the pioneers in this field, stands out for its high fracture toughness, strength, ductility and hardness. Research has explored the use of LAE as a substitute for cemented carbide, with promising results. The aim of this study was to evaluate the viability of the CrMnFeCoNi alloy as a substitute for tungsten-based carbide (WC-Co), using powder metallurgy with high-energy milling (HEM) and sintering via SPS. MAE, carried out for 10, 20 and 30 hours, proved to be effective in forming LAE, promoting deformation, fractures and cold welding of the particles. After 30 hours of milling, the CFC phase of the alloy was predominant, with amorphization of the secondary phases. In the WC-10%CrMnFeCoNi composite, MAE influenced the morphology and size of the particles, resulting in good dispersion of the phases and high incorporation of the alloy into the WC particles, even after only 10 minutes of mixing. XRD analysis revealed the WC and LAE phases, with no indication of chemical reactions or impurities. Sintering at 1200 °C resulted in almost uniform microstructures, with good dispersion of the WC particles in the binder matrix and low porosity. The composite with LAE milled for 30 hours showed better homogenization and dispersion of the phases, which favoured sintering and reduced porosity compared to the other samples. EDS analysis confirmed these results. The microhardness values of the samples varied, with 1786.9 HV1 (10 hours), 1643 HV1 (20 hours) and 1864 HV1 (30 hours). The best result was observed for the composite produced with LAE ground for 30 hours, as it showed greater homogenization and less porosity, resulting in an increase in microhardness.

COMMITTEE MEMBERS:
Presidente - 2414250 - MEYSAM MASHHADIKARIMI
Interno - 2345599 - BISMARCK LUIZ SILVA
Interno - ***.121.804-** - UILAME UMBELINO GOMES - UFRN
Externo à Instituição - MARCELLO FILGUEIRA