Effects of Boron Addition on the Microstructure and Mechanical Properties of (Ti,Ta)(C,N)-Co Based Cermets

Abstract

In this work, a titanium-tantalum carbonitride based cermet, with cobalt as the binder phase and boron as a sintering additive, was developed by a mechanically induced self-sustaining reaction process using two different methodologies. The boron additive was added to prevent the formation of brittle intermetallic compounds generally formed during the liquid phase sintering step due to the excessive ceramic dissolution into the molten binder phase. A systematic study was carried out to understand the effects of boron addition on the nature of the phases, microstructure, and mechanical properties of cermets. With the boron addition, the formation of two different boride solid solutions, i.e., (Ti,Ta)B 2 and (Ti,Ta) 3 B 4 , was observed. Moreover, the nature of the binder was also modified, from the (Ti,Ta)Co 2 brittle intermetallic compound (for cermets without boron addition) to ductile and tough (Ti,Ta)Co 3 and α-Co phases (for cermets with boron addition). These modifications caused, as a general trend, the increase of hardness and toughness in cermets.

A Novel Approach by Spark Plasma Sintering to the Improvement of Mechanical Properties of Titanium Carbonitride-Reinforced Alumina Ceramics

“…In most TiCN-based cermets, the binder phase is mainly composed of metals, and the solid solution hardening of the binder phase plays an important role in the application of cermets [ 6 ]. While increasing interest in Ti(C,N)-based cermets as a tool material has been observed from the early 1970s, improvements in the mechanical properties of these materials through the application of novel techniques of consolidation were widely discussed in the last decade [ 27 , 28 , 29 , 30 , 31 ]. Therefore, Ti(C,N)-based cermets with binder metals (Mo, Ni, and Co) and different secondary carbides (WC, NbC, TaC, HfC, VC, Cr 3 C 2 , and Mo 2 C) were manufactured using the vacuum hot-pressing process, the mechanically induced self-sustaining reaction process, microwave sintering, spark plasma sintering, and sintering in an induction furnace [ 21 , 27 , 28 , 29 , 30 , 31 , 32 ].…”

A Review on Fatigue Mechanisms and Approaches for Hard metals

“…The testing methods of cemented carbide tools used are generally mechanical tests such as tensile and compressive testing, micro cantilever, hardness test which consumes a lot of time and materials [24]. Therefore, hardness value is considered as an important mechanical property of metals and significantly this increases the performance and wear resistance of hard metals [25]. The micro-cantilever and Tensile testing were used in investigations of strength and deformability of the Tungsten carbide (WC) grains [26] and tungsten carbide boundaries were exposed according to strength of fracture which influences crack tip [27].…”

“…The fatigue crack growth (FCG) threshold determined the validation of subsequent actual toughness under repeated loading [42]. The fatigue surface normally starts on edges of contact area due to the result of reciprocation tensile and compressive stresses [43], these stress are well known for triggering fracture and eventually fatigue failure in brittle and ductile materials [24], [25]. The wear resistance provided by hard material ensures binder metal is appropriate and provides firm foundation for monotonic loading where cobalt (Co) is special choice formetal binder.…”

A Review of Research Progress on Ti(C,N)-Based Cermet Binder by Intermetallic Compounds and High-Entropy Alloys

“…The conventional binder phases Fe, Co, and Ni have good wettability to Ti(C,N), and Ti(C,N) has a certain solubility in them, which can ensure the high densification of the sintered cermet [23][24][25][26][27][28][29][30][31]. The microstructure of Ti(C,N)-based cermet is shown in Figure 2.…”