Influence of Temperature on Mechanical Properties of AMCs

E.S Caballero,Jesús Cintas,Petr Urban,Francisco G Cuevas,Fátima Ternero

doi:10.3390/met10060783

Abstract

This research focused on studying the effect of temperature on the mechanical properties of aluminium matrix composites (AMCs) obtained by a powder metallurgy route. Aluminium powder was milled at room temperature for 5 h and using different atmospheres in order to achieve different amounts of reinforcement. The atmospheres employed were vacuum, confined ammonia, and vacuum combined with a short-time (5 and 10 min) of ammonia gas flow. After mechanical alloying, powders were consolidated by cold uniaxial pressing (850 MPa) and vacuum sintering (650 °C, 1 h). Hardness and tensile tests, on consolidated samples, were carried out at room temperature. Subsequently, the effect of temperature on both properties were evaluated. On one hand, the UTS and hardness were measured, again at room temperature, but after having subjected the sintered samples to a prolonged annealing (400 °C, 100 h). On the other hand, the tensile and hardness behaviour were also studied, while the samples are at high temperature, in particular 250 °C for UTS, and in the range between 100 and 400 °C for hardness. Results show that the use of ammonia gas allows achieving mechanical properties, at room and high temperature, higher than those of the commercial alloys EN AW 2024 T4, and EN AW 7075 T6.

Highlights

Nowadays, lightweight alloys are extraordinarily attractive for industries such as transport, because they make it possible to reduce weight, which will translate into a reduction in fuel consumption and polluting effects [1,2].in the automotive and aeronautics industries, aluminium and its alloys play an important role in a wide range of structural applications [3,4,5]
There is a limiting factor for their use: the mechanical properties of aluminium alloys can be degraded when the material is exposed to temperatures above 100 ◦ C (373 K)
One of the possible ways to improve the properties of aluminium alloys is to reinforce them with ceramic particles, obtaining aluminium matrix composite materials (AMCs)

Summary

Introduction

Lightweight (low-density) alloys are extraordinarily attractive for industries such as transport, because they make it possible to reduce weight, which will translate into a reduction in fuel consumption and polluting effects [1,2].in the automotive and aeronautics industries, aluminium and its alloys play an important role in a wide range of structural applications [3,4,5]. There is a limiting factor for their use: the mechanical properties of aluminium alloys can be degraded when the material is exposed to temperatures above 100 ◦ C (373 K). It is of great interest to improve the properties of aluminium, both at room and at high temperatures, mainly in terms of reducing properties degradation. One of the possible ways to improve the properties of aluminium alloys is to reinforce them with ceramic particles, obtaining aluminium matrix composite materials (AMCs). These AMCs have interesting properties for industry, such as excellent wear resistance, higher specific resistance and higher resistance to thermal degradation, compared to conventional aluminium alloys [6,7]. Other properties of AMCs are their improved corrosion resistance, good thermal and electrical conductivity, and high

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