{"id":2470,"date":"2023-11-22T02:48:13","date_gmt":"2023-11-22T02:48:13","guid":{"rendered":"https:\/\/met3dp.com\/?p=2470"},"modified":"2023-11-22T02:49:17","modified_gmt":"2023-11-22T02:49:17","slug":"titanium-aluminum-alloys-20231122","status":"publish","type":"post","link":"https:\/\/met3dp.sg\/id\/titanium-aluminum-alloys-20231122\/","title":{"rendered":"Paduan aluminium titanium"},"content":{"rendered":"\n

Overview<\/h2>\n\n\n\n

Titanium Aluminum Alloys<\/a> are a class of metallic materials that contain a mixture of titanium and aluminum. They are lightweight, have high strength, and excellent corrosion and oxidation resistance at high temperatures.<\/p>\n\n\n\n

TiAl alloys are considered an important high-temperature structural material for aerospace and automotive applications due to their unique combination of properties. Their low density makes them lighter than nickel-based superalloys, while still retaining strength and stability at temperatures up to 750\u00b0C.<\/p>\n\n\n\n

Key Properties of <\/strong>Titanium Aluminum Alloys<\/h3>\n\n\n\n
Property<\/th>Description<\/th><\/tr><\/thead>
Density<\/td>3.7 – 4.1 g\/cm3, much lower than nickel alloys<\/td><\/tr>
Strength<\/td>Retain high strength at temperatures up to 750\u00b0C<\/td><\/tr>
Stiffness<\/td>High elastic modulus of about 160 GPa<\/td><\/tr>
Ductility<\/td>Brittle at room temperature but becomes more ductile at high temperatures<\/td><\/tr>
Corrosion Resistance<\/td>Excellent corrosion resistance due to presence of titanium<\/td><\/tr>
Oxidation Resistance<\/td>Form protective oxide layer resulting in good oxidation resistance up to 750\u00b0C<\/td><\/tr>
Cost<\/td>More expensive than titanium alloys but cheaper than nickel alloys<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
\"titanium<\/figure>\n\n\n\n

Types of Titanium Aluminum Alloys<\/h2>\n\n\n\n

There are two primary types of titanium aluminum alloys:<\/p>\n\n\n\n

Gamma TiAl Alloys<\/h3>\n\n\n\n

Gamma TiAl alloys have a lamellar microstructure and contain about 45-48% titanium, with the remainder aluminum. Small additions of elements like niobium, carbon, boron and chromium are also made to enhance properties.<\/p>\n\n\n\n

The gamma phase TiAl alloys offer a good balance of low density, strength, ductility and oxidation resistance. They are the most widely used TiAl alloys.<\/p>\n\n\n\n

Alpha-2 Ti3Al Alloys<\/h3>\n\n\n\n

Alpha-2 Ti3Al alloys contain about 25% aluminum and have a hexagonal crystal structure. They offer very high tensile strength but have lower ductility and fracture toughness compared to gamma TiAl alloys.<\/p>\n\n\n\n

Alpha-2 alloys are typically used in very high temperature applications above 800\u00b0C such as in turbochargers.<\/p>\n\n\n\n

Composition of Titanium Aluminum Alloys<\/a><\/strong><\/h2>\n\n\n\n

Titanium aluminum alloys contain titanium as the major component, with aluminum and small amounts of other elements. Here is the typical composition range:<\/p>\n\n\n\n

Alloy Element<\/th>Composition Range<\/th>Role<\/th><\/tr><\/thead>
Titanium (Ti)<\/td>52-56%<\/td>Primary base element<\/td><\/tr>
Aluminum (Al)<\/td>44-48%<\/td>Main alloying element with Ti<\/td><\/tr>
Niobium (Nb)<\/td>Up to 2%<\/td>Increases strength and creep resistance<\/td><\/tr>
Chromium (Cr)<\/td>Up to 2%<\/td>Increases oxidation resistance<\/td><\/tr>
Boron (B)<\/td>Up to 0.2%<\/td>Improves ductility<\/td><\/tr>
Carbon (C)<\/td>Up to 0.1%<\/td>Increases strength<\/td><\/tr>
Silicon (Si)<\/td>0.1-1%<\/td>Improves oxidation resistance<\/td><\/tr>
Tungsten (W)<\/td>0.1-1%<\/td>Refines grain size<\/td><\/tr>
Molybdenum (Mo)<\/td>0.1-1%<\/td>Increases strength<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

The percentages of alloying elements are precisely controlled to achieve the right microstructure and properties in the alloy.<\/p>\n\n\n\n

Key Properties of Titanium Aluminum Alloys<\/strong><\/h2>\n\n\n\n

Titanium Aluminum Alloy Strength Properties<\/h3>\n\n\n\n
Property<\/th>Value<\/th>Description<\/th><\/tr><\/thead>
Tensile Strength<\/td>500 – 1100 MPa<\/td>Very high strength compared to titanium alloys<\/td><\/tr>
Yield Strength (0.2% offset)<\/td>400 – 1000 MPa<\/td>Measure of elastic strength in alloy<\/td><\/tr>
Compressive Strength<\/td>600 – 1500 MPa<\/td>Excellent compressive strength<\/td><\/tr>
Creep Strength<\/td>100 – 350 MPa<\/td>Ability to withstand loads at high temperatures<\/td><\/tr>
Fracture Toughness<\/td>15 – 35 MPa\u221am<\/td>Resistance to crack propagation is lower than nickel alloys<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Physical Properties<\/h3>\n\n\n\n
Property<\/th>Value<\/th><\/tr><\/thead>
Density<\/td>3.7 – 4.1 g\/cm3<\/td><\/tr>
Melting Point<\/td>1360\u00b0C – 1460\u00b0C<\/td><\/tr>
Thermal Conductivity<\/td>6 – 25 W\/mK<\/td><\/tr>
Electrical Resistivity<\/td>150 – 250 \u03bc\u03a9.cm<\/td><\/tr>
Coefficient of Thermal Expansion<\/td>11 – 13 x 10<sup>-6<\/sup> \/K<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Mechanical Properties at Room Temperature<\/h3>\n\n\n\n
Property<\/th>Value<\/th>Description<\/th><\/tr><\/thead>
Hardness<\/td>300 – 400 HV<\/td>Measure of resistance to indentation<\/td><\/tr>
Young’s Modulus<\/td>150 – 160 GPa<\/td>Measure of stiffness<\/td><\/tr>
Shear Modulus<\/td>60 – 65 GPa<\/td>Measure of rigidity<\/td><\/tr>
Poisson’s Ratio<\/td>0.25 – 0.34<\/td>Ratio relating strain in directions perpendicular and parallel to applied load<\/td><\/tr>
Machinability<\/td>Difficult<\/td>Challenging to machine compared to steels<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n