• An alloy is a mixture of two or more metals. There are different kinds of alloys, such as alloys of magnesium, potassium, aluminum, iron, silver, gold, tin and lead. The mechanical properties of an alloy metal include the tensile, yield and ultimate strength, elongation, shear strength, hardness, impact resistance, endurance limit and compressive yield strength.
  
  

Tensile Strength

• The maximum stress the alloy metal can withstand without any breakage is called the tensile strength. It is measured in force per unit area. The minimum stress required to create an irreversible deformation is called the yield strength. Nonferrous metals do not have a yield point, as is the case in a magnesium alloy. For a magnesium alloy, if a stress-strain curve is drawn, then the stress at which it deviates 0.2 percent from the offset point is defined as the yield strength. The highest stress the alloy can withstand before it breaks is called the ultimate strength. The yield strength of titanium alloy is 830 Pa ("Pascal"), and its ultimate strength is 900 Pa. The yield strength of aluminum alloy is 414 Pa, and its ultimate strength is 483 Pa. The yield strength of high-strength steel alloy is 690 Pa, and its ultimate strength is 760 Pa.
  
  

Elongation

• When the alloy is subjected to stress, the fractional increase in length caused is called elongation. If the alloy is made of a ductile metal, then its stretching capacity is more. Thus, the percentage of elongation is a measure of the ductility of the alloy. A 6061-T6 aluminum alloy has an elongation of 10 percent, whereas red brass (a copper alloy) has an elongation of 35 percent.
  
  

Shear Strength

• The maximum stress the alloy can withstand when a shear force is applied, that is, without stretching or compression, is called the shear strength. The shear strength of an aluminum alloy is 83 Pa, whereas that of magnesium alloy is about 140 Pa.
  
  

Hardness

• The measure of the resistance exhibited by an alloy to surface abrasion is called its hardness. Alloys are made to be less brittle, harder and more resistant to corrosion than the pure metal. The alloys that exhibit the higher ductility and toughness are the iron alloys, which are combined with higher levels of carbon.
  
  

Impact Resistance

• Impact resistance is a measure of the amount of impact required for breakage of the alloy.
  
  

Endurance Limit

• The maximum stress the alloy can withstand without any failure in its function for a predefined minimum stress is called the endurance limit.
  
  

Compressive Yield Strength Stress

• The maximum stress the alloy can withstand when subjected to compression is called the compressive yield strength.
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