Ballistic performance of powder metal Al5Cu-B4C composite as monolithic and laminated armor

In this study, ballistic performances of x wt.-% B4C (x = 5, 10, and 20) reinforced Al5Cu matrix composite samples were investigated as a monolithic and laminated composite armor component. Composite armor plates were produced by the powder metallurgy method. The prepared powders were pressed under 400 MPa pressing pressure. Green compacts were pre-sintered at 400 °C for 30 minutes in order to blow the lubricant. Subsequently, liquid phase sintering was performed at 610 °C for 210 minutes. In ballistic tests, 7.62 mm caliber armor-piercing bullets were used as the ballistic threat. In the ballistic tests of monolithic armors, only 10 mm thick powder metal composite plates were tested. In the ballistic tests of laminated composite armors, these powdered metal plates were layered with 10 mm thick alumina ceramic plate front layers and 10 mm thick AA5083 plates. Although all of the monolithic powder metal composite armors were penetrated, they showed multi-hit capability. All of the laminated composite armors provided full ballistic protection. It was determined that with the increase in B4C reinforcement rate, the ballistic resistance also increased due to the improvement in strength, hardness, and abrasive feature.

MATHEMATICAL MODEL OF THE DYNAMICS DISPERSED MEDIA IN THE SHAPING PROCESSES BILLETS OF POWDER METALLURGY

A mathematical model has been developed for changing the dynamics of the movement of a dispersed medium in vibro-impact technological processes of shaping of powder metallurgy blanks. On the basis of the problem of two-dimensional dynamic interaction of dispersed particles of powder metal of a spacer dispersed medium, the obtained differential equation in partial derivatives under various boundary conditions. This equation describes the state of the local area of the dispersed medium. In it, the powder material of the workpiece passes from the concentrated dynamic force to the excitation phase. A partial differential equation is obtained. It describes the change in normal stress during vibrations of a dispersed medium during vibration compaction of a workpiece in powder metallurgy.

Influence of Machine Parameters on Ti-6Al-4V Small Sized Specimens Made by Laser Metal Powder Deposition

The present work is focused on one Additive Manufacturing (AM) process – Laser powder Metal Deposition (LMD-p) – and on one metallic alloy – Ti-6Al-4V. State of the art on LMD-p on Ti-6Al-4V alloy shows that three kinds of process parameters influence mechanical properties of building parts: raw materials (powder and substrate), machine parameters (Laser Power (P), Powder Flow (F) and Building Speed (V)), and building strategies (part orientation, waiting time between layers, etc.). Thus, this paper relates to first manufacturing investigations on small sized specimens (bead, wall and block) with the aim of providing a better knowledge about the first steps of manufacturing. Particularly, this paper is dedicated to the study of machine parameters (P, F and V). First, the influence of each machine parameter on 28 beads is studied separately. The geometrical aspect (high, width, dilution) of each bead is microscopically measured. Similarly, combinations of parameters (P/F, Energy Density and Powder Density) are introduced to increase parameters degree of freedom. First results show that P, V and F have a major influence on the beads’ geometry. In addition, a window process map is plotted and allows determining functional areas of machine parameters. From this map, walls (vertical superposition of one bead) are manufactured and microscopically observed. Functional sets of parameters from walls are selected and blocks can be built.

Nitriding during powder production and study of the structure of EP741NP alloy doped with nitrogen

The development of modern technics is limited by the physical and mechanical characteristics of the produced alloys, properties of which are often determined and enhanced by introduced alloying components. One of the alloying elements that have been very actively introduced in recent years is nitrogen. As a rule, alloying with nitrogen is carried out by ferroalloys, less often by gaseous nitrogen, which has significant advantages. In the processes of special electrometallurgy, alloying with nitrogen can be performed using, for example, nitrogen-containing plasma. Such a method may be feasible in the production of powder metal by spraying the ingot with nitrogen-containing plasma. It is known that performance properties of the products made of powder metal are significantly higher than those of cast metal. This served as a stimulus for investigating the properties of a product obtained from nitrided powder alloy EP741NP. In this work, a study of changes in the chemical composition, microstructure and microhardness of EP741NP alloy samples was carried out. The studied material was nitrided metal powders made on a plasma centrifugal spraying (PREP) unit and ingots from granules obtained by hot isostatic pressing (HIP). The chemical composition of the obtained samples was determined by wave dispersion X-ray fluorescence spectrometry. In order to study the microstructure of metal powders and ingots, the methods of scanning electron microscopy with EDXS were used. Microhardness of the samples was assessed using a microhardness tester by the Vickers method. The analysis of gas impurities was carried out on a gas analyzer. It is shown that nitriding of heat-resistant nickel alloy EP741NP is possible at the stage of metal powder production, without significant loss of alloying components and a sharp change in chemical composition. An increase in microhardness of the obtained nitrided samples was noted in comparison with the initial one.

Plasma Nitriding Mechanisms of Low-Density Sintered Metal Products

The mechanism of plasma nitriding include the formation of various active species generating nitrogen atoms reacting with the metal. Which species prevail in supplying nitrogen depends on nitriding conditions as well as the nature of the treated metal. Plasma nitriding of low-density powder metal (PM) products results in a formation of the layers whose thicknesses may depend on the gas pressure used for the process. Higher pressure can cause locally deeper penetration of the surface by active nitrogen species formed from ammonia compounds generated by the plasma. While a low processing pressure reduces this effect significantly. The formation mechanism of a locally thicker layer relies on the presence of open porosities in the surface as they can be penetrated by the ammonia species generated by the plasma. The same porosities cannot be penetrated by the ions of nitrogen formed at the same time since their mean free life is much shorter than that of ammonia species. ◼

WIELAND DURO TZM

Wieland Duro TZM is a molybdenum-titanium-zirconium-carbon alloy produced from pressed-and-sintered billets. Compared to unalloyed molybdenum, it exhibits higher recrystallization temperature and enhanced high-temperature strength and creep strength. Wieland Duro TZM is typically used between 700 and 1400 °C (1290 and 2550 °F) in a non-oxidizing environment. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on high temperature performance as well as machining and powder metal forms. Filing Code: Mo-20. Producer or source: Wieland Duro GmbH.