Influence of Ti and TiH 2 Additives on the Structure and Properties of Copper Alloys for Diamond Cutting Tools
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ICAL METALLURGY AND HEAT TREATMENT
Influence of Ti and TiH2 Additives on the Structure and Properties of Copper Alloys for Diamond Cutting Tools P. A. Loginova, *, S. Vorotiloa, **, D. A. Sidorenkoa, ***, Yu. V. Lopatinaa, ****, A. Okubayeva, *****, N. V. Shvyndinaa, ******, and E. A. Levashova, ******* aNational
University of Science and Technology “MISiS”, Moscow, 119049 Russia *e-mail: [email protected] **e-mail: [email protected] ***e-mail: [email protected] ****e-mail: [email protected] *****e-mail: [email protected] ******e-mail: [email protected] *******e-mail: [email protected]
Received December 27, 2019; revised March 9, 2020; accepted March 11, 2020
Abstract—The influence of titanium and titanium hydride additives on the structure, mechanical properties, and wear resistance of copper alloys intended for use as a binder of the diamond cutting tool is investigated. Powder mixtures Cu–Ti and Cu–TiH2 are fabricated by mechanical alloying in a planetary centrifugal mill. Such treatment makes it possible to form single-phased powders of the copper-based solid solution in the Cu–Ti system and two-phased powders based on copper with uniformly distributed TiH2 particles in the Cu– TiH2 system. It is established that the maximal mechanical properties are characteristic of the samples of compositions Cu–2.5% Ti and Cu–10% TiH2 (higher than for pure copper by a factor of 2.0–3.5). Hardening in such alloys is implemented according to the solid-solution mechanism and due to the formation of the Cu3Ti3O phase. Grains of this phase have higher dispersity in alloys where TiH2 is used as the titanium-containing additive, due to which high values of the bending ultimate strength (920 MPa) and hardness (114 HB) are attained. It is established according to the results of comparative tribological investigations that samples of the Cu–10% TiH2 composition possess the best wear resistance. The reduced wear of these samples after the test according to the “rod–disc” scheme is an order of magnitude lower than for pure copper and lower by a factor of 5 than for Cu–2.5% Ti samples. Keywords: diamond, diamond tool, copper alloys, mechanical alloying, strength DOI: 10.3103/S1067821220040069
INRTRODUCTION Due to its high thermal conductivity, plasticity, and availability, copper is widely used in the composition of binders of diamond tools [1–5]. Pure copper has two substantial disadvantages limiting its application in a diamond tool: its relatively low mechanical properties and a lack of interaction with carbon. The latter is the reason for the low diamond-holding strength of the superhard material in the working layer of the tool [6, 7]. Therefore, copper binders are alloyed with titanium, chromium, iron, nickel, and other components [8–10]. Copper–titanium alloys or titanium bronzes are widely used when producing diamond tools [11, 12]. Alloying the copper alloy by titanium promotes hardening (solid-solution or due to isolation of intermetallic compounds) and improves binder adhesion to dia-
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