Recent years have witnessed the booming of applications of powder metallurgy components in various fields such as aviation, automobile, structural, and precision engineering. At the time of powder metallurgy process, components have been produced to net shape by mixing different metal and non-metal powders to each other, followed by compaction, and sintering at elevated temperature. Considering this great advancements in the field of powder metallurgy, various composites have been prepared. Among the powder metallurgy parts, nearly 80% parts have been prepared from the ferrous alloy. The ferrous powder metallurgy has enormous potential for industrial applications in machines components, automobile parts, gears, lock and structural parts, etc. due to improved mechanical properties [1–3]. The performance of P/M components has governed by additions of an alloying element like carbon, copper, nickel, etc. [4–5]. In addition to this, the process parameters like sintering temperature and condition have vital effect in the assessment of mechanical properties of the ferrous alloy [6–7]. In general, for P/M components, solid and liquid phase sintering mechanism have been commonly used as techniques. During the solid phase sintering, the diffusion has occurred while during liquid phase sintering, the melting of alloying elements has been taken place at the sintering temperature and the densification increases through devolution of liquid metal [8–9]. In powder metallurgy component, usually, the graphite powder has added as a primary alloying element to increase density and hardness with reduced ductility [10–11]. Many researchers have reported that the addition of copper and graphite resulted in good strength and hardness of ferrous alloy [12–16]. The strength of ferrous alloy has improved due to an interstitial solid solution of carbon and liquid phase sintering of copper. The copper has the key alloying element to activate the sintering process by forming the liquid phase. In sintering, Fe particles have been surrounded by liquid copper for grain bonding. After solidification, liquid copper leads to the generation of microporosity [17]. In sintering of ferrous alloy, two different kinds of porosity have been observed. The primary porosity has developed during powder compaction and of large size and can be controlled during sintering but secondary porosity contains of minor pores frequently generated in sintering, due to passing melted alloying elements. These small secondary pores have generated by liquid phase sintering of copper particles [18–19]. The porosity and mechanical properties have been affected due to various processing characteristic viz. alloying additions, sintering time and temperature, compaction pressure, composition with binder amount [20–24]. Thus, porosity mainly the affects mechanical properties and also create difficulties in machining of P/M components as internal porosity leads to the formation of micro-vibrations in the cutting tool [25–26]. In this regard, to reduce porosity and enhance the machining properties of powder metallurgy components, the mineral clay has been mixed with metal powder [27]. The study of reduced porosity by an addition of fly ash on density, mechanical properties and microstructure of magnesium alloy has been carried out [28]. The natural bentonite clay has been mixed with the iron oxide as the mixture of bentonite clay and water formed a sticky mass which has excellent adhesive properties and used as a bonding agent between metal particles [29].
In this context, the mechanical properties of sintered ferrous clay composite having bentonite clay as a porosity filler were investigated. The natural sodium base bentonite (Aluminum Silicate) clay has been carefully chosen due to its admirable adhesive property. For studying the influence of wt. % of clay on mechanical properties of powder metallurgical component, the density and porosity have been measured and also the crushing and hardness test has been conducted. Also, microstructure analysis has been carried out by optical microstructure study and scanning electron microscopy (SEM) for study of clay particles location and X-ray diffraction (XRD) and Energy Dispersive Spectrometry (EDS) analysis for studying chemical composition of clay.