Microstructural evolution and strengthening behavior in in-situ magnesium matrix composites fabricated by solidification processing

Abstract

In-situ magnesium matrix composites with three different matrix materials (including Mg, AZ91 and AE44 Mg-alloys) were fabricated by injecting cross-linked polymer directly into the molten Mg/Mg-alloys, and having it convert to the 2.5 vol% SiCNO ceramic phase using liquid stir-casting method. In-situ chemical reaction took place within the molten slurry tending to produce 42 and 18 vol% Mg 2 Si crystals in Mg and AE44 matrix composites, respectively but not in AZ91 matrix composite. Microstructural evolution of Mg 2 Si crystals was discussed on the basis of availability of heterogeneous nucleation sites and amount of Al-atoms in the molten slurry. The observed micro-hardness and yield strengths are enhanced by factor of four to three as compared to their unreinforced counterparts, and Taylor strengthening was found to be the predominant strengthening mechanism in magnesium and AE44 matrix composites. Summation model predicted the yield strengths of the fabricated composites more preciously when compared to Zhang and Chen, and modified Clyne models.

Validation of Novel Geometrically Necessary Dislocations Calculation Model Using Nanoindentation of the Metal Matrix Nanocomposite

“…As in the previous case, the average diameter of the loop remains the same, with the prismatic loop coming near the surface of the sphere. Let A be the area of the averaged dislocation loop, which is pd 2 16 (the average loop diameter can be assumed as d/2), and q C be the total length of dislocation per unit volume. Ignoring the effect of the cooling rate,…”

“…[17] Local yield strength is further estimated as 360.4 MPa using an empirical relation. [2,15,18,19] 3. Discussion The mechanical properties of MMCs depend on the size and distribution of reinforcements.…”

“…THE reduced weight of structural elements is one of the prime requirements for aerospace, automotive, electric vehicle, biomedical, and tribological applications. [1,2] Metals are alloyed or reinforced with different phases to increase the strength and other characteristics. Understanding of strengthening mechanisms can reduce the experimental cost for engineering alloys/metal matrix nanocomposites (MMnCs).…”

“…The development of GNDs through incompatibility between the matrix and reinforcement has a dominant contribution in the strengthening of MMnC. [2] So the accurate calculation of GNDs is very important. Kujur et al [11] developed Mg-based MMnC with at most 1.5 vol pct ceria nanoparticles.…”

Development of SiC Nanoparticles and Second Phases Synergistically Reinforced Mg-Based Composites Processed by Multi-Pass Forging with Varying Temperatures

“…In fact, combinations of the above strategies may be beneficial to achieve desired properties. Previous research has shown that designed magnesium matrix composites with refined grains can enhance both strength and ductility [ 8 , 9 , 10 ]. Among the various reinforcements, discontinuous ceramic nanoparticles have outstanding advantages such as chemical inertness, isotropic properties and excellent mechanical properties, which make them attractive for the preparation of magnesium matrix composites [ 11 , 12 , 13 , 14 ].…”