Q - Shipwrecks & Salvage (1 Viewer)

[McLake]

What is a "strong" metal (see section 7 of syllubus).

Our teacher dosn't know. Does yours? Do you?

 

[bilal]

ok. its simple.. well... a strong metal is a metal, which is not very ductile and malleable... (we already know that metalz are not brittle).. so they are judged on their ductility and malleability.

in another context a strong metal maybe one which does not rust (oxidize) very quickly.

all this carbon crap, thats for an alloy. a METAL is pure. so aluminum metal has only aluminum in it. however an aluminum alloy may have carbon in it. that carbon (im not sure of this) may make it stronger.

 

[McLake]

Thanks

 

[Weisy]

which is not very ductile and malleable... (we already know that metalz are not brittle)..

just to add my two cents - I was always under the impression that carbon made a metal more brittle - hence the "stressed areas" of a piece of non-passivating metal rust more quickly, due to the carbon in the metal alloy which becomes clustered around it.

so... can the strength of a metal be defined by now brittle it is? (considering that if it is brittle, it is not malleable or ductile, and these can be thoughtof what makes a metal 'soft')

 

[bilal]

hey.. wiesy.. umm.. ure question.. if i understand it right, heres the answer:

ummm.. metalz can never be BRITTLE!!! it is a property of metalz to be ductile and malleable..

ummm.. alloys, however, of metalz and carbon can be brittle!!

and yeah.. their strength is probabally determined by that... how brittle they are, if they can be broken into pieces or not...

the only thing im not sure about is that an alloy of a metal and carbon, is brittle?!?!?! the more the carbon the more the brittle..
actually that may be right.. cuz an alloy is made manly for its physical properties.. its a physical change aswell..

carbon compound is brittle.. and if u mix it with a metal... well yeah.. actually.. i think it'll be a mixture of ductility, maleablity and umm.. brittleness!?!!??!
cuz its all physical..!?!??!
what du think?

is there an alloy which has like over 15-50% of carbon in it?
cuz i doubt the carbon will start showing its properties unless theres a large amount.. atleast 20-30%

 

[toja]

well... as far as i have a clue i guess the carbon can make the metal/alloy whatever stronger, as it goes in the little spaces in the metal lattice... however, when there is too much instead of strengthening the alloy it destroys the orderly arrangement of the lattice and hence makes it somehow brittle....... therefore the carbon content cant be more than a few percent, maybe 1 or two...

 

[bilal]

aaaaaaaaaaaaaaaaaaAAAAAAAAAAaaaaaaaaaaaaaaaaaaa
ummm.......
but wouldnt the metal properties be 99 times the carbon properties (if theres 1 percent carbon)??

hummm....

depends on how it mixes actually....
cuz if the metal atom is surrounded by carbon. it'll be brittle.
if carbon is surrounded by metal, well then, it'll be very hard.. cuz thats the "filling the spaces inbetween" thing ure talking about...

its stupid how i sumtimes, ask a question... and then end up answering it myself!?!?!?

 

[mannnnndy]

im not exactly sure how it works, but I know that pig iron is 3-4% carbon, and its very hard and brittle. it also corrodes really fast so maybe thats why steel with 15-20% carbon isnt used.

 

[Weisy]

sorry, my technical error about metals.

I guess I was referring to metals in a more 'everyday sense' being 'brittle', seeing as even the iron we use in nails, magnets, etc are slightly alloyed.

The presence of a small proportion of one or more additional elements in a metal can alter some of its properties significantly. In general, alloys are harder than pure metals. This is because the different sized atoms of other atoms interrupt the orderly arrangement of atoms in the metal lattice and prevent them from sliding over each other as easily. Hence 'carbon steel' (or the abovementioned 'pig iron') has up to 3-4% iron and not more than 1.7% manganese and 0.6% silicon. I guess it was just a 'trial and error' thing for early chemists to obtain the optimum proportion of each substance in order to produce an alloy with the properties most befitting to purpose.

My earlier question was not a question of whether metals are brittle, but whether the hardness of a metal is the same as its 'brittleness'. On that note, I think I have worked out the answer. Since different sized atoms in alloys interrupt the orderly arrangement of atoms in the lattice and hence they cannot slide easily past each other, they must in turn be more brittle since it is less likely they are able to be stretched or bent without breaking on impact.

Any takers?

 

[stuffed4exams]

Originally posted by Weisy


just to add my two cents - I was always under the impression that carbon made a metal more brittle - hence the "stressed areas" of a piece of non-passivating metal rust more quickly, due to the carbon in the metal alloy which becomes clustered around it.

so... can the strength of a metal be defined by now brittle it is? (considering that if it is brittle, it is not malleable or ductile, and these can be thoughtof what makes a metal 'soft')

it rusts faster not because the carbon weakens it, but because it is an impurity!!

 

[mannnnndy]

The carbon in steel acts as the cathode, so the more carbon the faster the steel will corrode.