Docsity
Log inSign up
Docsity
Prepare for your exams
Prepare for your exams

Study with the several resources on Docsity

Earn points to download
Earn points to download

Earn points by helping other students or get them with a premium plan

Guidelines and tips
Guidelines and tips
Sell on Docsity
Sell on Docsity
Log inSign up

Prepare for your exams

Study with the several resources on Docsity

Find documents

Prepare for your exams with the study notes shared by other students like you on Docsity

Search Store documents

The best documents sold by students who completed their studies

Search through all study resources
Docsity AINEW

Summarize your documents, ask them questions, convert them into quizzes and concept maps

Explore questions

Clear up your doubts by reading the answers to questions asked by your fellow students

Earn points to download

Earn points by helping other students or get them with a premium plan

Share documents
download point icon20 Points

For each uploaded document

Answer questions
download point icon5 Points

For each given answer (max 1 per day)

All the ways to get free points
Get points immediately

Choose a premium plan with all the points you need

Study Opportunities

Choose your next study program

Get in touch with the best universities in the world. Search through thousands of universities and official partners

Community

Ask the community

Ask the community for help and clear up your study doubts

University Rankings

Discover the best universities in your country according to Docsity users

Free resources

Our save-the-student-ebooks!

Download our free guides on studying techniques, anxiety management strategies, and thesis advice from Docsity tutors

From our blog

Exams and Study
Go to the blog

6 Questions on Phase Transformations in Material Processing - Exam 3 | MATL 6300, Exams of Materials science

Auburn University (AU)Materials science
Prof. Dong-Joo Kim

Material Type: Exam; Professor: Kim; Class: PHASE TRANSFORMATIONS IN MATERIAL PROCESSING; Subject: Materials Engineering; University: Auburn University - Main Campus; Term: Spring 2010;

Typology: Exams

2012/2013

Uploaded on 03/16/2013

dixiedigger88
dixiedigger88 🇺🇸

11 documents

1 / 5

Toggle sidebar

This page cannot be seen from the preview

Don't miss anything!

bg1
Page 1 of 5
MATL 5300/6300/6306 Spring 2010
Exam #3
Time Allowed 75 min
Name
PLEASE READ THE FOLLOWING BEFORE STARTING
• Please answer all questions in the space provided.
• No credit will be given for irrelevant answers, so please READ THE QUESTIONS with care!
• Credit is given for method as well as for solutions so it is essential that you CLEARLY show how
your answers were derived.
• Put labels and units properly.
1. Can you have a displacement of the Matano interface in a diffusion couple from the original weld
interface without a Kirkendall marker shift? Explain why or why not.
pf3
pf4
pf5

Partial preview of the text

Download 6 Questions on Phase Transformations in Material Processing - Exam 3 | MATL 6300 and more Exams Materials science in PDF only on Docsity!

MATL 5300/6300/6306 Spring 2010

Exam

Time Allowed 75 min

Name

PLEASE READ THE FOLLOWING BEFORE STARTING

  • Please answer all questions in the space provided.
  • No credit will be given for irrelevant answers, so please READ THE QUESTIONS with care!
  • Credit is given for method as well as for solutions so it is essential that you CLEARLY show how your answers were derived.
  • Put labels and units properly.
  1. Can you have a displacement of the Matano interface in a diffusion couple from the original weld interface without a Kirkendall marker shift? Explain why or why not.

_________________________________________________________________

  1. An A-B diffusion couple has been analyzed at a composition XA = 0.65 where X (^) A is the atom

fraction. The interdiffusion coefficient ( D = X DB A + X DA B ) was determined to be 5.5x10- cm 2 /sec and ∂ X (^) A / ∂ x = 2.44 cm -1^. Experimentally it has been determined that the markers move

in a manner described by the following equation:

2 x (^) t = K

where K is a constant, x is the distance moved by the markers from the Matano interface, and t is the diffusion time. For XA = 0.65 and 50 hours diffusion time, x = 0.01 cm.

(a) What is the velocity of the markers in cm/sec? (b) Determine the numerical values of the intrinsic diffusion coefficients DA and DB. Note that the

velocity of the markers in terms of diffusion constants can be expressed by (^ A B )^ A

X

v D D X

_________________________________________________________________

  1. What degree of undercooling is required to insure homogeneous nucleation occurs in alloy ufailum? Properties of alloy ufailum are as follows: Tm = 600 oC, γs-l (interfacial energy between solid and liquid) = 200 erg/cm^2 , L (latent heat) = − 2x10^3 J/cm 3 , r* (critical nucleus size) =1.5x10 -7^ cm. Remember that 1 erg = 10-7^ J.

_________________________________________________________________

  1. The following is a schematic of the diffusion couple consisting of A and B which form a substitutional alloy. Assuming DA < DB, determine (a), (b), and (c). (a) Marker position after diffusion (b) Line of pores (Kirkendall porosity) after diffusion (c) Net flux of vacancies
  2. Draw two curves corresponding to homogeneous and heterogeneous nucleation on each plot.

Marker

A B

∆GLÆS

r

∆T

Nucleation rate (I)