In Situ Synthesis of Al-Based MMCs Reinforced with AlN by Mechanical Alloying under NH₃ Gas.

E Caballero,F Ternero,F Cuevas,J Montes,R Astacio,J Cintas

doi:10.3390/ma11050823

Abstract

Aluminum matrix composites (AMCs) reinforced by aluminum nitride were prepared by mechanical alloying followed by a simple press and sintering method. Milling began under vacuum and after a period of between 1 and 4 h, NH3 gas flow (1 cm3/s) was incorporated until the total milling time of 5 h was reached. Results show that in addition to the strain hardening taking place during mechanical alloying, NH3 plays an additional role in powder hardening. Thereby, the properties of the sintered compacts are strongly influenced by the amount of N incorporated into the powders during milling and the subsequent formation of AlN during the consolidation process. The obtained AMC reaches tensile strengths as high as 459 MPa and hardness much higher than that of the as-received aluminum compact.

Highlights

Because of their low weight and moderate strength, aluminum alloys are of great interest for a wide range of structural applications, especially in the aerospace and automotive industries [1,2].the increasing demand for a high specific strength and properties stability at elevated temperatures [3,4] make necessary the development of new aluminum alloys
The increasing demand for a high specific strength and properties stability at elevated temperatures [3,4] make necessary the development of new aluminum alloys. The improvement of these properties can be achieved through new aluminum matrix composites (AMCs) [5,6,7], which are based in an aluminum matrix reinforced by ceramic particles
The as-received aluminum powder was attrition milled under different cycles of vacuum (5 Pa) and ammonia gas flow (1 cm3/s)

Summary

Introduction

The increasing demand for a high specific strength and properties stability at elevated temperatures [3,4] make necessary the development of new aluminum alloys. The improvement of these properties can be achieved through new aluminum matrix composites (AMCs) [5,6,7], which are based in an aluminum matrix reinforced by ceramic particles. Because of their excellent properties, AMCs are nowadays widely used in sectors such as transportation, aerospace, electronics, sports, and infrastructure industries [8,9]. There are several methods by which to produce AMCs, including stirring casting [15], pressure infiltration [7,10,16], spray deposition, accumulating roll bonding [17], centrifugal casting [18], and powder metallurgy [19]

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Results

Conclusion