Effect of strain rate on the formation of the microstructure of a 1950/10% SiC metal matrix composite under high temperature

The present work deals with the high temperature flow behavior and the microstructure of the Al-Cu/Mg2Si metal matrix composite. Toward this end, a set of hot compression tests was performed in a wide range of temperature (573–773 K) and strain rate (0.001–0.1 s−1). The results indicated that the temperature and strain rate have a significant effect on the flow softening and hardening behavior of the material. The work hardening rate may be offset due to the occurrence of the restoration processes, the dynamic coarsening, and spheroidization of the second phase particles. In this regard, two phenomenological constitutive models, Johnson–Cook (JC) and Arrhenius-type equations, were employed to describe the high temperature deformation behavior of the composite. The JC equation diverged from experimental curves mainly in conditions which are far from its reference temperature and reference strain rate. This was justified considering the fact that JC model considers thermal softening, strain rate hardening, and strain hardening as three independent phenomena. In contrast, the Arrhenius-type model was more accurate in modeling of the flow behavior in wide range of temperature and strain rate. The minor deviation at some specified conditions was attributed to the negative strain rate sensitivity of the alloys at low temperature deformation regime.

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High-Temperature Synthesis of Metal–Matrix Composites (Ni-Ti)-TiB2

Applied Sciences ◽

10.3390/app11052426 ◽

2021 ◽

Vol 11 (5) ◽

pp. 2426

Author(s):

Vladimir Promakhov ◽

Alexey Matveev ◽

Nikita Schulz ◽

Mikhail Grigoriev ◽

Andrey Olisov ◽

...

Keyword(s):

High Temperature ◽

Composite Materials ◽

Metal Matrix Composite ◽

Matrix Composite ◽

Metal Matrix ◽

Average Particle Size ◽

Synthesis Process ◽

Average Particle ◽

Temperature Synthesis ◽

High Temperature Synthesis

Currently, metal–matrix composite materials are some of the most promising types of materials, and they combine the advantages of a metal matrix and reinforcing particles/fibres. Within the framework of this article, the high-temperature synthesis of metal–matrix composite materials based on the (Ni-Ti)-TiB2 system was studied. The selected approaches make it possible to obtain composite materials of various compositions without contamination and with a high degree of energy efficiency during production processes. Combustion processes in the samples of a 63.5 wt.% NiB + 36.5 wt.% Ti mixture and the phase composition and structure of the synthesis products were researched. It has been established that the synthesis process in the samples proceeds via the spin combustion mechanism. It has been shown that self-propagating high-temperature synthesis (SHS) powder particles have a composite structure and consist of a Ni-Ti matrix and TiB2 reinforcement inclusions that are uniformly distributed inside it. The inclusion size lies in the range between 0.1 and 4 µm, and the average particle size is 0.57 µm. The obtained metal-matrix composite materials can be used in additive manufacturing technologies as ligatures for heat-resistant alloys, as well as for the synthesis of composites using traditional methods of powder metallurgy.

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