Indentation Plastometry of Particulate Metal Matrix Composites, Highlighting Effects of Microstructural Scale

Herein, it is concerned with the use of profilometry-based indentation plastometry (PIP) to obtain mechanical property information for particulate metal matrix composites (MMCs). This type of test, together with conventional uniaxial testing, has been applied to four different MMCs (produced with various particulate contents and processing conditions). It is shown that reliable stress–strain curves can be obtained using PIP, although the possibility of premature (prenecking) fracture should be noted. Close attention is paid to scale effects. As a consequence of variations in local spatial distributions of particulate, the “representative volume” of these materials can be relatively large. This can lead to a certain amount of scatter in PIP profiles and it is advisable to carry out a number of repeat PIP tests in order to obtain macroscopic properties. Nevertheless, it is shown that PIP testing can reliably detect the relatively minor (macroscopic) anisotropy exhibited by forged materials of this type

Profilometry‐Based Indentation Plastometry at High Temperature

This is a first report on profilometry‐based indentation plastometry (PIP) at high temperature (HT), covering both thermal characterization and issues for obtaining stress–strain curves. The heating system has a relatively low thermal inertia, reaching 800 °C within about 10 min, while both indentation (≈20 s) and cooling (≈20 min) are also quick. This capability is useful in terms of limiting exposure of the sample to prolonged periods at HT, and hence avoiding the formation of thick oxide layers (which can affect indent profiles and hence inferred stress–strain curves). There is good general consistency between stress–strain curves obtained via HT‐PIP and those from tensile testing. However, the possibility of creep (time‐dependent deformation) affecting the outcomes (of both types of test), particularly at higher temperatures, should be borne in mind. Creep has a characteristic effect on tensile curves, which can often be confirmed and investigated by changing the imposed strain rate. It can also be revealed by carrying out the HT‐PIP testing with different penetration velocities or by monitoring the shape of the load–displacement plot