Showing 4 results for Liquid Phase Sintering
H. Momeni, H. Razavi, S. G. Shabestari,
Volume 8, Issue 2 (6-2011)
Abstract
Abstract: The supersolidus liquid phase sintering characteristics of commercial 2024 pre-alloyed powder was studied at different sintering conditions. Pre-alloyed 2024 aluminum alloy powder was produced via air atomizing process with particle size of less than 100 µm. The solidus and liquidus temperatures of the produced alloy were determined using differential thermal analysis (DTA). The sintering process was performed at various temperatures ranging from the solidus to liquidus temperatures in dry N2 gas atmosphere for 30 min in a tube furnace. The maximum density of the 2024 aluminum alloy was obtained at 610ºC which yields parts with a relative density of 98.8% of the theoretical density. The density of the sintered samples increased to the maximum 99.3% of the theoretical density with the addition of 0.1 wt. %Sn powder to the 2024 pre-alloyed powder. The maximum density was obtained at 15% liquid volume fraction for both powder mixtures.
A. Mohammadzadeh, A. Sabahi Namini, M. Azadbeh,
Volume 11, Issue 3 (9-2014)
Abstract
The rapidly solidified prealloyed alpha brass powder with a size range of 40 to 100 μm produced by water
atomization process was consolidated using liquid phase sintering process. The relationships between sintering
temperature, physic-mechanical properties and microstructural characteristics were investigated. Maximum
densification was obtained at 930 °C, under 600 MPa compacting pressure, with 60 min holding time. The
microstructure of the sintered brass was influenced by dezincification and structural coarsening during supersolidus
liquid phase sintering. As a consequence of Kirkendall effect atomic motion between Cu and Zn atoms caused to
dezincification at the grain boundaries and formation of ZnO particles on the pore surfaces. It was concluded that
microstructural analysis is in a well agreement with obtained physical and mechanical properties. Also, the amount of
liquid phase, which depends on sintering temperature, results in different load bearing cross section areas, and it
affects the type of fracture morphologies.
H. Momeni, S. Shabestari, S.h. Razavi,
Volume 17, Issue 4 (12-2020)
Abstract
In this research, densification and shape distortion of the Al-Cu-Mg (Al2024) pre-alloyed powder compact in the supersolidus liquid phase sintering process (SLPS) were investigated. The effect of Sn on the sintering process was also studied. The powders were compacted at pressures ranging from 100 to 500 MPa in a cylindrical die. The sintering process was performed in a dry N2 atmosphere at various temperatures (580-620 ºC) for 30 min at a heating rate of 10 ºCmin-1. Results showed that the onset of densification process was observed at 600ºC and onset of distortion was occurred at 610ºC. Addition of 0.1 wt. %Sn to the alloy has increased the distortion of the samples produced from Al-Cu-Mg pre-alloyed powder, but their densification has been improved. The compact pressure of 200MPa caused the complete densification at the optimum sintering temperature and at the compact pressures greater than 200MPa; the sintered density was independent of green density.
Mahdi Rajaee, Mahdi Raoufi, Zeinab Malekshahi Beiranvand, Abbas Naeimi,
Volume 22, Issue 2 (6-2025)
Abstract
This research explored the impact of the nickel-to-manganese ratio and the influence of the matrix phase on the properties of W-Ni-Mn tungsten heavy alloys (WHAs), aiming to determine the optimal composition for achieving desirable alloy properties. For this purpose, tungsten, nickel, and manganese powders with specified weight percentages underwent two rounds of wet milling. Powder mixtures were obtained with weight ratios of 90W-6Ni-4Mn, 90W-8Ni-2Mn, and 88W-10Ni-2Mn. These mixtures were then compressed through the cold pressing method at a pressure of 250 MPa. Subsequent reduction and sintering processes were carried out in a tube furnace at temperatures of 1150 and 1400 °C, respectively. Microstructural characterization was conducted using both optical and electron microscopy. The results showed that the change in chemical composition is not significantly effective on the sintering density of the samples and also the highest sintering density, reaching 90.11%, was achieved with the 88W-10Ni-2Mn sample. Furthermore, the results demonstrated that carburization of W-Ni-Mn WHAs during the sintering process led to an increase in the micro-hardness of the samples. The highest hardness, measuring 381 Hv, was observed in the 90W-6Ni-4Mn alloy, where carburization occurred. XRD results revealed that an increase in the nickel-to-manganese ratio led to a reduction in the peaks of manganese carbide and tungsten carbide. Consequently, this decrease in carbide peaks resulted in a reduction in hardness, reaching 352 Hv in the case of the 88W-10Ni-2Mn sample. Additionally, the alloys 90W-6Ni-4Mn and 88W-10Ni-2Mn both exhibited the lowest continuity, a value of 0.5. Fracture surface SEM images illustrated that the 90W-6Ni-4Mn alloy, characterized by the lowest nickel-to-manganese ratio (1.5), exhibited the highest trans-granular fracture mode involving cleavage and matrix tearing, which is considered desirable. Furthermore, an increase in the matrix phase content resulted in a shift of the preferred crack path, originating from the matrix phase.
