High strain rate superplasticity in metal matrix composites: the role of load transfer

The mechanical behavior of titanium alloys has been mostly studied in quasi-static conditions when the strain rate does not exceed 10 s−1, while the studies performed in dynamic settings specifically for Ti-based composites are limited. Such data are critical to prevent the “strength margin” approach, which is used to assure the part performance under dynamic conditions in the absence of relevant data. The purpose of this study was to obtain data on the mechanical behavior of Ti-based composites under dynamic condition. The Metal Matrix Composites (MMC) on the base of the alloy Ti-6Al-4V (wt.%) were made using Blended Elemental Powder Metallurgy with different amounts of reinforcing particles: 5, 10, and 20% of TiC or 5, 10% (vol.) of TiB. Composites were studied at high strain rate compression ~1–3·103·s−1 using the split Hopkinson pressure bar. Mechanical behavior was analyzed considering strain rate, phase composition, microstructure, and strain energy (SE). It is shown that for the strain rates up to 1920 s−1, the strength and SE of MMC with 5% TiC are substantially higher compared to particles free alloy. The particles TiC localize the plastic deformation at the micro level, and fracturing occurs mainly by crushing particles and their aggregates. TiB MMCs have a finer grain structure and different mechanical behavior. MMC with 5 and 10% TiB do not break down at strain rates up to almost 3000 s−1; and 10% MMC surpasses other materials in the SE at strain rates exceeding 2200 s−1. The deformation mechanism of MMCs was evaluated.

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High strain rate deformation in particle reinforced metal matrix composites

Acta Materialia ◽

10.1016/1359-6454(95)00236-7 ◽

1996 ◽

Vol 44 (3) ◽

pp. 1011-1019 ◽

Cited By ~ 54

Author(s):

G. Bao ◽

Z. Lin

Keyword(s):

High Strain Rate ◽

Strain Rate ◽

Metal Matrix Composites ◽

Metal Matrix ◽

High Strain ◽

Matrix Composites ◽

High Strain Rate Deformation

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Electron Microscopy of Metal-Matrix Composites

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100069016 ◽

1970 ◽

Vol 28 ◽

pp. 404-405

Author(s):

A. Lawley ◽

M. R. Pinnel ◽

A. Pattnaik

Keyword(s):

Electron Microscopy ◽

Metal Matrix Composites ◽

Metal Matrix ◽

Critical Evaluation ◽

Elastic Behavior ◽

Matrix Composites ◽

Directionally Solidified ◽

Fracture Characteristics ◽

Broad Program

As part of a broad program on composite materials, the role of the interface on the micromechanics of deformation of metal-matrix composites is being studied. The approach is to correlate elastic behavior, micro and macroyielding, flow, and fracture behavior with associated structural detail (dislocation substructure, fracture characteristics) and stress-state. This provides an understanding of the mode of deformation from an atomistic viewpoint; a critical evaluation can then be made of existing models of composite behavior based on continuum mechanics. This paper covers the electron microscopy (transmission, fractography, scanning microscopy) of two distinct forms of composite material: conventional fiber-reinforced (aluminum-stainless steel) and directionally solidified eutectic alloys (aluminum-copper). In the former, the interface is in the form of a compound and/or solid solution whereas in directionally solidified alloys, the interface consists of a precise crystallographic boundary between the two constituents of the eutectic.

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