Explain why some metals like lead and tin do no strain harden when deformed at room temperature.?
85947
These metals are softer than others (ex. steel) and will self-anneal at room temperature, thus counteracting the strain hardening.
636584
"Many metals, such as copper, bronze, silver, brass, and some steels, readily react with solder to form strong chemical and physical bonds. Other metals, such as aluminum, high alloy steels, cast iron, and titanium, range from very difficult to impossible to solder."\n\n"Soldering Hints\nA useful *anti-flux* is ordinary toothpaste."
421541
Metals, Nonmetals, & Metalloids\n\nMost periodic tables contain a stairstep line which allows you to identify which elements are metals, nonmetals, and metalloids. Following are descriptions of each of the three types of materials.\n\nMetals\n\nMost elements are metals. 88 elements to the left of the stairstep line are metals or metal like elements.\n\nPhysical Properties of Metals:\n\nLuster (shininess) \nGood conductors of heat and electricity \nHigh density (heavy for their size) \nHigh melting point \nDuctile (most metals can be drawn out into thin wires) \nMalleable (most metals can be hammered into thin sheets) \nChemical Properties of Metals:\n\nEasily lose electrons \nCorrode easily. Corrosion is a gradual wearing away. (Example: silver tarnishing and iron rusting) \nNonmetals\n\nNonmetals are found to the right of the stairstep line. Their characteristics are opposite those of metals.\n\nPhysical Properties of Nonmetals:\n\nNo luster (dull appearance) \nPoor conductor of heat and electricity \nBrittle (breaks easily) \nNot ductile \nNot malleable \nLow density \nLow melting point \nChemical Properties of Nonmetals:\n\nTend to gain electrons \nSince metals tend to lose electrons and nonmetals tend to gain electrons, metals and nonmetals like to form compounds with each other. These compounds are called ionic compounds. When two or more nonmetals bond with each other, they form a covalent compound.\n\nMetalloids\n\nElements on both sides of the zigzag line have properties of both metals and nonmetals. These elements are called metalloids.\n\nPhysical Properties of Metalloids:\n\nSolids \nCan be shiny or dull \nDuctile \nMalleable \nConduct heat and electricity better than nonmetals but not as well as metals
1111034
Perhaps the link will help a little.  If you bend a pipe or metal bar, some of the metal will be in tension (stretched) and some will be in compression (squeezed).  There is a neutral plane between the two conditions that is neither stretched nor squeezed.  Often the plane passes through the centroid of the pipe (or bar).  This is easy to find if the cross-section is regular (round, square, etc.) but more difficult to find if the area is irregular or of variable properties such as density.  The centroid is similar to the center of gravity for the shape.  Hope that helps a little.
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Metals are shiny and are good conductors of heat and electric current. They are malleable and ductile.\nNon-metals are dull, and are poor conductors of heat and electric current. They're brittle and unmalleable.
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ductility.  A ductile metal is easily shaped
194087
First you have to have understanding of their bonding.\n\nMetallic bond - Metallic bonding is the bonding within metals. It involves the delocalized sharing of free electrons among a lattice of metal atoms. These become delocalized electrons or sometimes called a Sea of Electrons surround a giant lattice of positive ions.\n\nWhy is it ductile?\n\nIt is ductile because the attracive forces between the free electrons and cations (positive ions) are very strong. However the cations are able to change its positions(ie change shape) but not seperated from the whole lattice structure.\n\nCeramic on the other hand is an ionic solid. Ionic bonds are a type of chemical bond based on electrostatic forces between two oppositely-charged ions. Often ionic bonds form between metals and non-metals.\n\ntake salt for example:\nhttp://www.geo.arizona.edu/xtal/geos306/9_2.jpg\n\nwhen the struture is changed as a result of impact (ie a piece of the block move downwards by one atom), the positive ions (Na+) changed its location, next to another Na+ ion. (same with the Cl- ion)so they repelled and causes the whole structure to fall apart (brittle).
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Solid, there are only 2 elements that are liquid at room temperature, Mercury, and Bromine. 2 other elements will melt from the heat of your hand, (slightly above room temperature), Cesium and Gallium.
425662
You may get specific crystalline structure of materials in solid state physics books.For example sodium it is difficult to draw out here. polycrystalline materials are cryatalline only that their crystallinity are not longrange but in small domains in the material. There are boundaries in between the domains and they are randomly oriented. Each domain is the perfect crystal.
488946
The length of any metal increases as the temperature rises. \n\nThe increase in length, for the same initial length is different for different metals for the same increase of temperature.\n\nIn bimetallic strips, two metals strips of same length are placed one over the other and are riveted at their ends.\n\nWhen these strips are heated, both strips increase in lengths but one increases more than the other.\n\nBut, as the ends are fixed, to accommodate the increase in length, both bend into arcs of a circle, the less increased strip form the  inner arc and the other form the outer arc.\n\nThis bimetallic strip is in contact with another strip and they are in series with the heating element of the iron. \n\nThis second strip can be depressed at will by means of a screw which can be operated externally.\n\nAs the temperature increases the bimetallic strip begins to bend but it is in contact with the second strip till a particular temperature reaches which is determined by the adjustment of the screw.\n\nWhen that temperature is reached the second strip ceases its contact with the bimetallic strip.
1148498
Conventional superconductors are made from alloys of niobium and titanium or niobium and tin.  The niobium-tin alloy can support higher currents and magnetic fields, but is more expensive and generally less easy to work with.  Superconducting wire usually consists of filaments of these alloys embedded in a copper matrix.  The copper provides mechanical stability for the filaments, which are somewhat brittle, and a place for the current to flow if the superconductivity is lost because of high temperature or magnetic field (superconductors are quite poor conductors when they "go normal").\n\nSuperconducting wire is durable and stable at room temperature, spools of it can sit on a laboratory shelf for decades and still be useful.\n\nThese conventional superconductors have transition temperatures down around 11 or 13 degrees Kelvin, so expensive liquid helium is just about the only practical way to run them.\n\nThe oxide superconductors discovered in the mid-1980s are, even now, still somewhat of a young field.  They have few industrial applications, though I believe they're used in thin coatings to provide high-quality radio-frequency oscillators.  The oxide superconductors are generally brittle, easily damaged by water, and difficult to work with.  \n\nThere are many recipes for the manufacture of oxide superconductors, and it is not too difficult to create a fused mass of small crystals of the compound generally referred to simply as "one two three", the yttrium barium calcium copper oxide material (funny, yahoo truncates that name when the chemicals are properly separated by hyphens).  Such a mass of crystals will not have zero resistance on an ohm-meter, but may levitate above a strong magnet if enough of the bulk is superconducting.\n\nLast I heard, the highest transition temperature materials were thallium-based variants of the bismuth strontium calcium copper oxides.  Because of the extreme toxicity of thallium, only professionals in well-equipped laboratories should try to make those compounds.
106147
It is just from the way that the elements are fused together to form the compound. It's the same as any other metal.
161431
The grain structure continually refines itself as the piece undergoes stress and strain. This is known as "work hardening". The ductility lessens, and the piece becomes more brittle.
55435
jtkeel is mostly right, except the structure of copper is not crystaline.  Al3K is right about the structure of copper, which is the basic structure of all metals and is what gives them their physical characteristics, like their malleability, conductivity and so forth.
572288
Copper is malleable any temperature above about -50C..certainly at room temperature, so I'm not sure what you mean by that question- It has a relatively high melting point (about 1100 C), but does not need to be hot to be worked.
1019278
Titanium is NOT the strongest metal.  It is often thought of as the strongest but actually it has one of the highest strength to weight ratios.  I.e., for a metal that is so light-weight, it is extremely strong.  Typically it has a ultimate tensile strength of up to 170,000 psi.  Another unique property is that its strength does not deteriorate in high temperature applications. This makes it ideal for use in aerospace especially engine components. \nThere are many metals much stronger than this.  Two stainless steels that come to mind are 17-4PH and 15-5PH which can achieve Ftu of 180,000 to 200,000 psi through heat treatment.\nInconel 625 which is used in the aerospace industry, typically in the production of high-strength fasteners used in critical joints can achieve ultimate shear strengths of 220,000 psi.\nIntermediate alloy steels such as 5Cr-Mo-V has an Ftu of up to 280 ksi.  Also low alloy steel such as AISI 4130 used in aircraft landing gear has extremely high bearing strength, tensile and compression strength.
880613
Do you see any high performance airplanes  or centrifuge rotors made of plastic instead of titanium?  I think you just answered your question. . .\n\nThat is a little glib, because tensile strength is only one mechnaical property (specific strength, hardness, etc). Stiffness is another reason titantium is popular.  Pure titanium has tensile strengths from 250 to 750 MPa. Ti alloys go up to 1250 MPa. \n\nIf you really only care about tensile strength in **one direction** then there are materials. Heat treatment of carbon fibers can generate tensile strengths as high as 5650 MPa.  Such fibers can be part of a plastic composite and nearly all of them will be less dense than titanium. Molecular weight is ill defined in such compounds and probably not what you meant.