Sintering Behavior and Mechanical Properties of NiAl, Al2O3, and NiAl-Al2O3 Composites

Abstract

It is commonly known that the properties of sintered materials are strongly related to technological conditions of the densification process. This paper shows the sintering behavior of a NiAl-Al 2 O 3 composite, and its individual components sintered separately. Each kind of material was processed via the powder metallurgy route (hot pressing). The progress of sintering at different stages of the process was tested. Changes in the microstructure were examined using scanning and transmission electron microscopy. Metal-ceramics interface was clean and no additional phases were detected. Correlation between the microstructure, density, and mechanical properties of the sintered materials was analyzed. The values of elastic constants of NiAl/Al 2 O 3 were close to intermetallic ones due to the volume content of the NiAl phase particularly at low densities, where small alumina particles had no impact on the compositeÕs stiffness. The influence of the external pressure of 30 MPa seemed crucial for obtaining satisfactory stiffness for three kinds of the studied materials which were characterized by a high dense microstructure with a low number of isolated spherical pores.

Application of the Hertz formulation in the discrete element model of pressure-assisted sintering

“…Figure 9 presents the evolution of relative density of NiAl specimen during initial powder compaction and pressureassisted sintering. Moreover, the graph shows the experimental results obtained by own studies, which have been widely described in [16,20,29]. The whole simulation has been divided into subsequent stages: loading, heating, sintering, cooling and unloading.…”

Metal-ceramic functionally graded materials – manufacturing, characterization, application

“…• C), high value of Young's modulus (stable when increasing temperature), high mechanical, fatigue, tensile and compressive strengths (also at high temperatures), and good frictional wear resistance [30][31][32].…”

Machinability improvement of powder metallurgy steels

“…In contrast to the metals produced by conventional alloying methods, the properties of powder metallurgy parts depend on the composition of the powder mixture, the compacting pressure, and the sintering conditions applied [1,2]. In fact, the international literature abounds in investigations, experimental results and data about the machining of steels produced in conventional metallurgy methods.…”