Unknown Gum Metal Facts: An Alloy Possessing High Strength

Gum metals, commonly referred to as TNTZ, are a one-of-a-kind titanium alloy with exceptional ductility, elasticity, and yield strength.

It was initially created with a composition of 0.7% tantalum, 23% niobium, 1% oxygen, and 2% zirconium. It can also come in a variety of other compositions, including vanadium and hafnium.

The mechanical properties of gum metal are excellent but peculiar. Gum metal has high yield stress (up to 1 GPa) and excellent elongation to failure when deformed under tension at room temperature (up to 35%).

History And Discovery Of Gum Metal

While gum metal existed, the mechanism underlying their behavior was unknown, making it challenging to use in applications. Scientists at Düsseldorf's Max-Planck-Institut für Eisenforschung (MPIE) have since discovered a new phase transformation in a titanium alloy, which could help us better understand how this behavior occurs. The word 'phase' relates to the crystal structure wherein the atoms are placed.

X-rays, atom probe tomography, and transmission electron microscopy were used by the researchers to identify abnormalities in the nanostructure of the alloy. Max Planck scientists were able to examine the crystal structure of the alloy during the transition using X-rays at the DESY accelerator center.

The MPIE researchers have found a new mechanism during phase change in this way. Jian Zhang's team discovered a novel structure called the omega phase, which arises when the beta phase transforms into the alpha phase.

Characteristics Of Gum Metal

Materials science is based on the study of material structure and how it relates to their properties, such as mechanical, electrical, etc. Once materials scientists understand the structure-property relationship, they can investigate the relative performance of materials in a certain application.

The tensile strength of the tin bronze gum metal is roughly 310 MPa. Ultimate tensile strength for aluminum ranges from 50 MPa to 3000 MPa for very high-strength steel. Tin bronze gun-metal has a yield strength of about 150 MPa. Tin bronze gunmetal has Young's modulus of elasticity of roughly 103 GPa. Tin bronze gunmetal has a Brinell hardness of 75 BHN.

Under mechanical stress, this titanium alloy exhibits certain interesting mechanical properties that arise from a 'dislocation-free' giant fault mechanism. The role of lattice dislocations in the process is still a subject of controversy. After the research, it was discovered that gum metal plasticity is governed by a massive fault mechanism that does not require direct aid from dislocations in the process.

The properties reveal that the alloy doesn't get harder or brittle when distorted, as metals generally do, but instead bends, somewhat like honey. It possesses an extremely low elastic stiffness and a very high ductility.

Applications Of Gum Metal

Bronzes are a group of copper-based alloys that have traditionally been alloyed with tin, often 12–12.5% tin. A limited portion of phosphorus (0.01–0.45) is added to boost fatigue resistance, hardness, and wear resistance. Such alloys are used in fasteners, springs, shafts, masonry fixes, gears, valve spindles, and bearings.

The alloy can be utilized as a crash absorber in the aerospace industry. Bronze, in the form of a high tin bronze alloy collectively known as bell metal, which is roughly 23% tin, is also the ideal metal for bells. High tin bronze alloys are commonly used in great-strength bushings, gears, and bearing applications that require high strength and large loads. Piston rings, pump impellers, and steam fittings are among the other uses for these metals.

The copper alloy for casting UNS C90500, popularly known as gun metal, is a cast copper-tin alloy. Steel has largely replaced it as the major material for weapon construction.

Use In Chemistry

Titanium alloys are usually found in two phases. The atoms are normally found in the alpha phase at room temperature, but they switch to the beta phase at high temperatures.

Depending on which phase they are in, metals have varying qualities. Gum metals are predominantly made up of the beta phase, which, in the case of these alloys, is stable at room temperature.

When the beta phase is quickly cooled from a high temperature, a few of the atoms move into the potentially better favorable alpha phase arrangement. The movements of atoms cause mechanical tension at the phase boundary, as if the phases were pulling with one other. Once this stress reaches a crucial level, a new arrangement, known as the omega phase, is implemented.

A new alpha phase layer bordering on an omega phase is generated once the stress falls below the critical value because of the new layer. This leads to a microstructure made up of several layers, many of which are on an atomic scale, each with its structure.

When alloyed with beta-stabilizing elements like V, Mo, Nb, W, or Ta, the resulting alloys can form a variety of other stable or metastable phases like hcp alpha', base-centered orthorhombic alpha' phases, non-close-packed hexagonal omega phases, and some intermetallic phases.

Researchers hope that the newly discovered structure will aid them in better understanding the mechanical and physical properties of materials and, eventually, the development of new, enhanced titanium alloys.

FAQs

Q. What is gum metal used for?

A. The alloy is ideal for a variety of industrial applications. It can be used as a crash absorber in the aerospace industry.

Q. What is gum metal made of?

A. Gum metal is made up of 0.7% tantalum, 23% niobium, 2% zirconium, and 1% oxygen, and it can come in a variety of components, like hafnium and vanadium.

Q. What is unique about gum metal?

A. Gum metal has several unique properties, including superplasticity and a low work hardening ratio at ambient temperature, low elastic modulus, nonlinear superelasticity, Invar and Elinvar behavior after extreme cold deformation.

Q. What color is gum metal?

A. Gum metal is dark gray with a bluish or purplish tinge.

Q. How common is gum metal?

A. Gum metal is a unique form of metal that can only be discovered in a few locations across the world. Aluminum, tin, and copper are among the metals used to make them. It's silvery in hue and extremely silky. Because of this, it's ideal for using in jewelry and other decorative products.