Ductility and malleability is a mechanical property of a material, which means that before the material is forced to fracturePlastic deformationAbility.
The property that an object can extend into filaments without breaking under the action of external force is calledductility；Under external force (hammering orRolling）The property that can be rolled into thin pieces without breaking is called expansibility.For example, metals have good ductility, including gold, platinum, copper, silver, tungsten and aluminum.Quartz, glass, etcNon metallic materialsIt also has certain ductility at high temperature.
Ductility isMetallic mineralsOne of the characteristics of metal minerals under external force isPlastic deformation, which means that ions can move and rearrange and lose their adhesion. This isMetal bondThe root cause of mineral ductility.The ductility varies with the degree of metal bond.
ductility
Structure, member or a section of a member reaches the maximum from yieldingcarrying capacityOr the deformation capacity during the period when the bearing capacity has not been significantly reduced after reaching.For structures with good ductility, members or a section of members have large deformation capacity in the later period, and can still absorb a certain amount of energy after reaching the state of yield or maximum bearing capacity, which can avoidBrittle failureOccurrence of.
Ductility is a physical property.It means that the materialPlastic deformationCapability is related to the ductility of materials.For example, gold, copper, aluminum, etcductilityMaterials.Platinum is the most ductile metal.
Brittle failure The structure or component has no obvious deformation or other types of premonitory failure before failure.Ductile failure(ductile failure) The type of failure in which the structure or component has obvious deformation or other omens before failure.
Under the impact and vibration loads, the materials of the structure are required to be able to absorb greater energy and produce certain deformation without damage, that is, the structure or component is required to have good ductility.For example, steel structure materials have good ductility and can resist strong earthquakes without collapse;andMasonry structureThe deformation capacity is poor, and it is easy to collapse due to brittle failure under strong earthquakes.For this purpose, masonrymasonry structureThe house shall be earthquake resistantSpecification requirementsset upStructural columnAnd seismic resistanceRing beam，confined masonry To increase its deformation in theearthquake action Collapse resistance under.reinforced concreteThe material has duality. If the design is reasonable, it can eliminate or reduce the harm of the brittle property of concrete, give full play to the plastic property of reinforcement, and achieveDuctile structure。For this reason, seismicreinforced concrete structure According toductilityStructure requirementsseismic design , to achieveearthquake fortification Three level requirements of: the structure is in elastic state under small earthquakes;Moderate earthquakeThe structure may be damaged, but it can continue to be used after repair;Major earthquakeThe structure may be damaged, but will not collapse or endanger life safety.
Ductility(conductivity and malleability) is determined byductilityThe two concepts of expansibility are similar in mechanical properties.Common metals and many alloys have ductility.
staymaterial science Medium,ductility(Liability) is that the material is subject toTensile stress（tensile stress）deformationThe ability of the material that is particularly noticeable.Ductility is mainly shown when the material is stretched into linear strips.Expansibility(Malleability) is another similar concept, but it indicates that materials are subject toCompressive stress(Compressive stress) The ability to deform without breaking.The malleability is mainly shown when the material is forged or rolled into thin plates.Ductility and malleability are not always related. For example, gold has good ductility and malleability, but lead only has good malleability.However, because these two concepts are similar, they are often calledDuctility。
Expansibility
The property of an object that can be pressed into sheets.Most metals are malleable, gold being the most.
The property that can be rolled into thin sheets without breaking under external force (hammering or rolling) is called expansibility.
give an example
In metal bonds, valence shell electrons can move freely between many atoms.Such characteristics are called "electronic sea".Since electrons can move freely, metal atoms can move relatively without great resistance.Gold is the most ductile metal, followed by aluminum.But many plastics andAmorphousSolids are also malleable.The metal with the best ductility is platinum Pt, and the metal with the best ductility is gold Au.
When a knife is used to carve a ductile mineral, the place where the mineral surface is carved immediately leaves bright grooves without powder or particles, which can be distinguished from brittleness.
Metal has ductility, which means that metal cantake a percentageFilament.For example, the diameter of the thinnest platinum wire is less than 1/5000mm.Metal is malleable, which means it can be pressed into thin sheets, such as the thinnestGold foilOnly 1/10000mm thick.The most malleable metal is gold.It is reported that 1. Someone extended 28 grams of gold to 65 kilometers long;2. One or two gold foils can cover two basketball courts.The ductility of metals can be explained by their structure.When the metal is subjected to external force, it is easy to makerelative displacement The metal is deformed and not easy to break, so the metal has goodDeformability。But there are also a few metals, such as antimony, bismuth and manganese, which are brittle and have no ductility.Therefore, it can only be said that general metals have ductility.
Metal ductility
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Because the radius of metal atoms is relatively large,valence electronThe number is relatively small, and electrons are easily separated from metal atoms and becomefree electron(delocalized electrons) that no longer belong to an atom.So, whencrystalsufferExternal force actionWhen, metalPositive ionSlipping without fracture (because there are still free electrons around) shows good ductility.
The essence of the interaction between metal positive ions and free electrons isPositive and negative ionsAttraction between, nonedirectionalAnd saturation.althoughIonic crystalContainedIonic bondIt is also directionless and unsaturated, but when the external force moves the ion layer, making ions with the same charge close,repulsionIncrease, resulting in no ductility of ionic crystals.
Law of ductility
Ductility is generally for metals, that is, forMetallic crystalFor other crystals, ductility is generally not considered.So which metals have better ductility?The ductility of active metals is often poor and inactiveMetal ductilityOften very good.For example:AuThe ductility of Ag, Pt is among the best,alkali metalandalkaline-earth metalThe ductility of is among the worst (in metals).Of course, the metal mercury has the worst ductility, because it is liquid under normal conditions.
influence factor
For stamping, mainly for iron, othersMetallic materialsIt is not without stamping, but less.One of the factors determining the ductility of iron materials is the internal structure of the metal. The internal structure of iron determines its ductility,MartensiteIts size and shape are closely related to the ductility of metal.Martensite is large with poor ductility, while martensite is small with good ductility. The size of martensite is related to the temperature change during heat treatment.Second, the ratio of iron to other metal materials is related. For example, the ductility of iron doped with tungsten and other elements is poor, while the ductility of iron doped with tin and other metals is better.
Extendability in the economy
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Extendability refers to the ability of enterprises to derive a series of new products andNew servicesTo meet the needs of customers.The core competitiveness depends on the corecompetitive power→core technology →Core products→Final productThe core competitiveness of an enterprise includes one or several core technologies, which cooperate to form one or more core products, and then derive the final product from the core products.In this extension process, the core competitiveness of enterprises is the leading force.
The extension of core competitiveness enables enterprises to meet the needs of customers to a large extent, not only the current needs, but also the potential needs.The satisfaction of this demand is achieved by giving full play to the extensibility of core competitiveness and actively applying it in new fields.The extensibility makes the core competitiveness more able to ensure the success of diversified development of enterprises.Taking Sharp as an example, its core competitiveness is LCD technology, which makes SharpNotebook computer, pocket calculator, large screen imaging technology and other fields have competitive advantages.
