Alloy

About: Alloy is a research topic. Over the lifetime, 171884 publications have been published within this topic receiving 1719420 citations. The topic is also known as: alloys.

Fundamental Aspects of Bulk Metallic Glass Formation in Multicomponent Alloys

Abstract: During the past several years, a number of multicomponent alloy families have been investigated in which the liquid alloys form metallic glass at cooling rates below 1000 K/s and as low as 1 K/s or less. These ``bulk`` metallic glass forming alloys have been cast from the melt into glass samples with the smallest dimension ranging from millimeters to centimeters. The undercooled liquid alloys show remarkable resistance to crystallization permitting studies of thermal and physical properties, the glass transition, and crystallization behavior of the melt over previously inaccessible temperatures in the deeply undercooled region. One group of these alloys, which includes the Zr-Ti-Ni-Cu-Be and Zr-Ti-Ni-Cu systems, has been extensively investigated in our laboratory. Results of atomic diffusion and viscosity measurements, crystallization behavior and TTT-diagrams, and studies of liquid phase separation in the deeply undercooled liquid have been carried out and will be discussed. Engineering properties and potential applications of these bulk glasses will be briefly mentioned. (orig.)

Flexible manufacturing of metallic products by selective laser melting of powder

Abstract: In order to produce metallic parts directly from powder material using CAD data, the selective laser melting (SLM) process has been developed. From a series of material tests, nickel-based alloy, Fe alloy and pure titanium powders are found to be feasible for fabrication of metallic models by SLM. Finite element simulation shows stress distribution within the solid single layer formed on the powder bed during forming and some methods for avoiding defects in the products are suggested. The die for metal forming from the nickel-based alloy and the pure titanium models of bone and dental crown are demonstrated. The density of the model made by SLM is higher than 90% of the solid model. The mechanical properties of the formed model can be improved to those of the solid by post-processing.

Hardness of tempered martensite in carbon and low-alloy steels

Abstract: This paper presents the results of a systematic study of the effect of carbon, manganese, phosphorus, silicon, nickel, chromium, molybdenum, and vanadium on the hardness of martensite in low to medium carbon steels tempered for one hour at 100°F (56°C) intervals in the range 400 to 1300°F (204 to 704°C). Results show that the as-quenched hardness depends solely on carbon content. On tempering, the effect of carbon on hardness decreases markedly with increasing tempering temperature. Studies of carbon-0.5 manganese steels showed that the incremental increase in hardness from 0.5 pct manganese after a given tempering treatment was independent of carbon content. Based on this result, studies of the effects of the other alloying elements were made using a 0.2 or 0.3 pct carbon, 0.3 to 0.5 pct manganese steel base composition. The hardness of the resulting tempered martensite was assumed to be due to a given alloy addition, and when two or more alloying elements were added, their effects were assumed to be additive. Each of the seven alloying elements increased the hardness of tempered martensite by varying amounts, the increase being greater as more of each element was present. Nickel and phosphorus have substantially the same effect at all tempering temperatures. Manganese has essentially the same hardening effect at any temperature in the range 700 (371°C) to 1300°F; silicon is most effective at 600°F (316°C), chromium at 800°F (427°C), molybdenum at 1000 to 1100°F (538 to 592°C), and vanadium at 1200°F (649°C). Using the data obtained, a procedure is established for calculating the hardness of tempered martensite for carbon and alloy steel compositions in the range studied and for any combination of tempering time and temperature.